27" iMac occasionally freezes up - newbie needs help!

Hey folks: I'm new to the forum and fairly new to the wonderful world of mac. We have a 27" iMac, late 2009 (2.66 ghz core i5 processor; 12 gb RAM; ATI Raedon HD 4850 512 MB graphics) running OS X 10.8.4. Bought it used last year, and for the most part it works fine.

But every once in awhile it just freezes up on me. I can still see the cursor moving around when I move the mouse, but can't click anything. Keyboard doesn't do anything. My only choice is to hold the power button down and do a hard reboot. I thought maybe it was a mouse/keyboard connectivity issue, maybe a bluetooth thing, but it doesn't appear so.

It has happened shortly (i.e. within an hour) after turning the computer on, and after hours of use... at one point I thought it was more prone to occur when I was using Google Chrome (I kind of live in Chrome), so I tried uninstalling Chrome, but it still happened, so there might not be a cause-and-effect relationship here; it may be simply that I'm in Chrome a lot, so it's more likely to happen when I'm in Chrome than any other application - I dunno. I'm not knowledgable enough about macs to know if there's a way to troubleshoot this.

Any help or suggestions or pointers in some direction would be MUCH appreciated. I will not take offense to any responses; feel free to assume I'm completely ignorant.

iMac, OS X Mountain Lion (10.8.4)

Posted on Jul 19, 2013 10:07 AM

19 replies

branhan Author

Level 1

0 points

Jul 20, 2013 5:37 PM in response to Baby-Boomer-USofA

LOL - no problem! Glad to know I'm not alone...

Oct 24, 2013 11:37 AM in response to branhan

I have the same imac and have the same problem. Once in a while it locks up and you can see the cursor but nothing works. I have to login via the command line from another machine and reboot it.

I've got a feeling that this is a hardware related problem.. I've got SMC fan controller installed and had not had any problems since increasing the fan speed. Today I've just rebooted after installing Mavericks and I got a lock up. I'm hoping that it's because SMC Fan controller wasn't running..

I've just restarted it and will have to see if the problem happens again. I was right in the middle of doing a job application that required me to fill in about 10 forms !

Simon

Dec 15, 2013 8:42 AM in response to branhan

Since I have the very same issue (different specs though: OS 10.6.8, 2.8 GHz, Core i7, iMac) I was just checking if anyone has discovered the cause and/or solution to this problem. I was thinking of upgrading to Mavericks to see if that would solve the problem but thought I'd look around first. It appears from Simonp123456's post that Mavericks may not be the answer.

Note: as the original poster described the problem, this is a lockup that allows the movement of the cursor but clicking doesn't work on anything (including the Mac menue) and the keyboard also produces no response. There is NO SPINNING BALL.

Feb 4, 2014 6:11 AM in response to s_leahcim

I am pretty sure this is a hardware issue, I was thinking pehaps I might try to re-seat the graphics card in the machine, but it's a lot of effort

It just happened again today ! it's pretty annoying, I can SSH on from another machine and run shutdown, however it doesn't actually power off the machine, which I'm thinking perhaps could be a related issue. Have upped the fan speed again to see if that makes a difference.

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27" iMac occasionally freezes up - newbie needs help!