Q: My cursor is going bananas.

I was having the same problem and changing to a different plug did the trick. I, too, have an Apple charger, btw. Thanks!

@nchaffet, it's been a few months since your last post.  Any news? 

My wife's 13" MacBook Pro just started doing this a couple days ago.  I took it to the Apple store, because she thought it was the trackpad (I didn't investgate beforehand), and the genius helping me did the CMD+R+P reset - think the Pram, as you mentioned - and it solved the issue...until I got home and my wife needed to use the computer. 

The cursor, mostly on internet browsers (Chrome, Firefox, and Safari), jumps, sticks, highlights, and unhighlights. Also, sometimes the ol' CMD+Tab menu pops up randomly.  I was thinking of going through the whole reformatting hard drive, and reinstall the OS, but wanted to check here before I went ahead and did that.  The only thing I worry about is I'll have to use Time Machine to bring back all her previous stuff, everything, and wonder if the issue will return.

Hopefully you'll still read these posts, and if anybody else has had a solution to this issue, please let us know.

Cheers

Since posting above (July 2, 2012) I have had no more cursor problems.

My suggestion is to move the computer to another room and plug it directly into a receptacle.  The reason it worked at the Apple store is that it was plugged into their electrical system and not yours.  Don't use a plug strip, plug directly into the outlet.  The reason for going into a different room is to try and get onto a different part of your electrical system.  The problem may have to do with your plug strip, your outlet, or the circuit they are on.

Also, don't expect immediate relief.  My impression is that it takes a bit before what (in my imagination) is a "charge" to wear off of the surface of the laptop.  Since my old Powerbook got into the same snit and was finally corrected by directly plugging into an outlet, I have pretty great faith that your problem will also be corrected.

To get it usable while waiting for the "charge" or whatever the magic is to wear off, suggest that you follow the following (magical) steps - keep it on a table, not on your lap, place a piece of thin plastic like half of a page protector over the track pad and lower area below the keyboard where wrists and arms touch the computer (I taped mine in place).  You may even have to try several receptacles before you get one that the laptop likes.  Also turn it off (not sleep) when not using until you get it solved.  The longer I used it in the crazy cursor condition, the worse it got.  

Good Luck, DB

@framer, thanks for your encouraging post.  I have read about the 'swollen' adapter.  This could very well be the case, but since your post 6 days ago there has not been much change.  Today, I have reset the PRAM two times consecutively, which has seemed to erradicate the issue temporariliy as it did in the Apple store originally. 

We are currently only plugging in her MacBook Pro in the other room directly to an outlet.  The odd thing is I have a 15" - a newer generation - and I have not experienced any such odd activity even when sharing the adapter.

Will keep posted.  Please let me know if there are any updates.

Cheers

I have this issue on a MacBook Pro 13", purchased in 2009, running Snow Leapard.

I work in the computer industry and have done troubleshooting on all different types of Operating Systems (UNIX/LINUX/Windows) in my 14 year career.

I am really leaning towards this problem being some kind of software issue, not hardware. Facts I have gathered on my system:

• It is NOT a battery issue. The battery health is fine and I have even removed the battery (despite the "do not remove sticker and tricky triangle screws holding it in) without affecting the problem.
• The issue is sporatic. Hardware issues typically are very persistent or get worse over time, this issue is sportatic and sometimes the mouse will work fine for up to 15-20 minutes, other times it occurs faster.
• Putting heavy pressure on the trackpad and running my fingers (while cursing) over the entire surface termporarily relieves the problem. (This seems to lean towards hardware being the issue)
• Cleaning the track pad ( I have fully removed it and cleaned it ) did not help. The Mac does not boot without the trackpad attached, so I could not completley rule out a faulty trackpad.
• PRAM reset or perhaps just a full reboot seems to fix it for a ~20 minute period.
• It occurs running on battery power and/or only on DC. (as I said, I have removed the battery)

Today, as I typed this on a Windows system, in prep to restore the Mac OS, I put the battery back in and unscrewed / unplugged the main fan, cleaned it, replaced it. I proceeded to backup my files on the Mac. While doing this, I was not connected to the Internet or using a browser at all. For a period of well over an hour, which is the longest I have seen since encountering this issue, the mouse stayed still when I was not using it. Perhaps the faulty software knew of my intentions and decided to finally behave? I previously thought this might be a heat issue, as in.. as the computer heats up, the mouse is affected. Apparently that theory is also out the door.

I wonder if since there are many of us having this issue at the same time that it's a Mac Software Update issue, which occurs due to some other software existing on the system.

I will continue to investigate this .. the next step I will likely take is an upgrade to Lion and if that fails, a complete hard disk wipe and restore.

So the one experiment I have yet to hear, and which seemed quite simple, was to plug in a USB mouse to see how the cursor responded.  Now, I have a Wacom Intuous 3 for my MacBook Pro (15" 2010 model), so it's not your 'normal' mouse, but nonetheless, a type of mouse to bypass the trackpad. 

[NOTE: ADAPTER IS PLUGGED IN] I plugged in the Wacom tablet, and the cursor stopped its nonsense and acted somewhat normal (I didn't have the Intuous drivers installed on her computer yet, so it wasn't perfectly calibrated).  Next, I decided to wipe her hard drive clean and reinstall the OS (10.5.8) to see if it were software related.  A bit later, without the Wacom tablet inputed, the installation was complete.  Cursor still was wanky.  Still sucked.  Still did it's random ghostly annoying things.  I plugged in the Wacom back in.  The cursor was working as it did before, but the odd thing was it was as if the mouse was left-clicking itself everywhere - if I hovered over something, it would activate it or open it. 

Next, I went to the Wacom website, downloaded the latest driver for my wife's computer.  Recalibrated the mouse and all, and everything worked like a charm all of a sudden, including the trackpad.  At this time, I removed the power cord from the computer, and let it sit.  Played with the cursor and the computer for awhile to test it.  Within 2-3 minutes the trackpad went back to its funky ways - stalling, clicking, highlighting, jumping, etc. - and the Wacom cursor worked fine, except for the fact the left-clicking started again on its own.  As of this moment I have the computer just sitting on a JPEG icon on Flickr, and it keeps opening and closing and opening and closing and I'm 10 feet from the computer. 

I don't know what all this means.  If it's the battery, if it's a malfunction in System software (bad function or something), or if it's another kind of hardware issue.  I do not have a mighty mouse or any other mouse, but if others have tried, please let us know.  Tomorrow I will retrun to the Apple store with the tablet and computer to show the major differences in the behavior of the cursor.  One thing is for sure, plugging in a USB mouse definitely changes the behavior.

Thanks

I just wanted to add my name to the list of the possessed cursor. I will admit that I eat over my macbook all the time and have never once opened the case to give it a proper cleaning. (I have cleaned it from the outside, even in the cracks with little swabs.)

I also have a cat that regularly sleeps on it, and originally I thought he bent the bottom case that was causing my trackpad button to stick at the most random, inopportune times. He also got caught up in the power cord once, causing the teeth on the plug to bend ... which I handily bent back with some pliers to seemingly no ill effect.

I notice it's better if I hover my hands over the keyboard and not let my wrists rest on the case. This also made me wonder if there was some type of static charge building up over the trackpad causing it to go all crazy, but I would think if that was the case it would have been happening all along. I'll try plugging it into a new place, that's an easy enough fix to see what happens.

I did try a wireless mouse with my new MacBook Pro (see post above).  The cursor still jumped around.  And regarding kmantics battery troubleshooting, I did the same thing on both the old Powerbook when it did this and on the new MacBook Pro.  Battery in/Battery removed/plugged in outlet/running on battery, it still did the same thing.  The only thing that corrected the problem was plugging the power cord directly into the wall socket. 

And mollysusie, I agree with your suggestion that it's a static charge issue.  And regarding the cleaning issue, since my MacBook Pro has not been cleaned, yet it is healed, I'm quite satisfied that it's not a matter of cat, or in my case dog, hair in the machine.

I always felt like this was potentially an over-heating issue - since it would work fine after a cold boot or even coming out of sleep when the system was 95% cold, then as it warmed up, the issue would occur.

As I stated yesterday, I had removed the battery for a few days to troubleshoot the problem. The problem seemed to take longer to manifest with the battery out, but happened nonetheless. So as I'm reinstalling the battery, towards the opposite side of the case, there's a 2"x2" fan. I notice that it's only got 3 screws holding it in, so I decide to remove it and give it a cleaning. It's visibly dusty. I remove it, unplug it (the connector pops straight up) and there's a large accumulation of dust behind it, between the fan and the vent to the outside. I would estimate that it was 20-30% clogged.

Prior to putting the battery back and cleaning the fan, I was prepared to reinstall the OS. However when I booted it back up and spent 2 hours backing up my data, I had zero occurrences of the mouse issue.

Obviously no one here has conclusively been able to determine exactly what the issue is related to, so I cannot say "clean the fan, that is the issue", but it is the only thing I've done (along with removing / reinstalling the battery) and the trackpad issue (so far) hasn't reproduced since doing it.

I will leave the system on for 2-3 hours today and see if the problem reoccurs.

A heat issue could also explain why placing your hands on the system while typing (as one person noted) vs. holding them over the keyboard without touching, affects the problem. They thought it was "static electricity", but it could in fact be that the aluminum case is transferring body heat. I wonder if there's an internal temperature reading that we could monitor to see if there's a correlation.

A heat issue would not explain why I can temporarily alleviate the issue by pressing firmly on the trackpad, however. But a software issue should not be affected by cleaning the fan and reinstalling the battery.

Installed this: http://www.bresink.com/osx/0TemperatureMonitor/download.php5

Screen shot of my temps after running for ~3 hours.. opened various programs, was watching a movie in iTunes:

Could be a good baseline for any experiencing the issue.. mine is still 100% flawless through 5-6 hours of use.

Problem reoccurred after 10-12 minutes of typing.. seems while the system was on, but not really being used (cursor/keyboard idle) the problem did not occur.

I did have a battery health widget on my old Powerbook that gave the same basic information.  I kept an eye on it because of having to replace the battery at about 4 years old (hard drive puked at 6 years old).  One of my concerns in general was the heat being generated and the apparent lack of a fan engaging.  Found out that in fact, the fan did work when necessary and they temperatures of the laptop stayed within specs.  I learned to "hear" the fan as it was very quiet.  Ditto with the new laptop.  I never was able to associate the cursor issue with a temperature issue. 

You've pretty much worked through all ofthe same troubleshooting that I did.  Something that we never did was actually check the receptacle with a meter.  The original problem with the Powerbook occurred when we had a 4 socket plug block plugged into a standard receptacle.  Plugging it directly into a different receptacle solved it's problem.  With the newer MacBook Pro, it was plugged into a very sturdy, fuse protected plugstrip and that was plugged into the receptacle that I ended up using for the Powerbook.  When MBPro acted up, I eliminated the plugstrip and plugged it back into the obviously good wall socket and have had no problems since. 

Just musing here because I don't know much about computers (and don't try this at home boys and girls) but would SAFELY grounding the aluminum case to a baseboard heating pipe be worth trying?  I've not done this and don't need to try it.  Perhaps it's an option KMantic might like to pursue since you seem to have a good handle on computer hardware/software. 

This problem is begging for a definitive answer as when it happens, its totally crazy and frustrating.  I showed my husband when it happened on the MBPro.  Without me touching the trackpad, the cursor was opening up file after file all across the desktop.  It was a lot like the I Love Lucy candy episode where the candy kept coming down the conveyor belt faster and faster.  What a nightmare that was. 

Today when I turned it on, it was already warm.. I think maybe someone else was using it before I got out of bed. The problem was there instantly. I rebooted, did the PRAM reset and pressed hard on the track pad but nothing would, even temporarily, alleviate the problem.

Turned it off for over an hour, let it cool.. (full shutdown) turned it back on.. the problem still existed.

I remembered I have the original hard drive, which was last used in 2010. I replaced it with a solid state drive back then, so the original still has a working operating system on it.

I put in the original hard drive, completely different OS, booted up .. problem was there and exactly the same.

Problem occurred while on battery power only, plugged into a surge protector and 2 different wall outlets.

Has to be hardware at this point, but doesn't seem to be the battery.. nor hard drive. So I am leaning towards the trackpad itself as the next target. My dad has nearly the same model, I think the trackpads are interchangeable. So if he'll humor me, I may swap them out to see if that affects the problem. Otherwise, next stop.. Apple Store.. and I hate having others fix my stuff!

Decided to chill my mac by putting it in the fridge for an hour..

Mouse worked, but not super-smooth for maybe 1-2 minutes.. then started clicking itself again. So at this point, I'm not even sure it's a heat issue. I should have checked the temperature readings, but I'm pretty sure it didn't have time to shake the 40F degree chill in under 2 minutes with zero apps open.

Will be a few days before I can get the trackpad replaced to see if that fixes it.

Have not replaced the trackpad.. however, after some more googling - my latest (yes, I know I've had a few) theory is that it's a bad ground inside the mac. Seems the touchpads are very sensitive to static and that may also explain why the issue is so sporatic.. from non-existent to useable but not smooth movements to clicking all over the screen.

http://reviews.cnet.com/8301-13727_7-10330102-263.html