Spinning wheel of death

1. Go to the Spotlight icon at the top right of your screen:

2. Type activity monitor in the search field (where it says "sandra" in the picture above)

3. The "top hit" will be the Activity Monitor app. Click it. The Activity Monitor utility will appear.

4. Read the following KB article to decipher its meaning:

Using Activity Monitor to read System Memory and determine how much RAM is being used

5. Reply with the numbers shown for "page ins" and "page outs" like you see in the following.

Also, reply with the total amount of memory installed in your system - it is the number below the "pie chart" in the above screenshot.

Now that you are an Activity Monitor expert, you can use it to identify what specific processes are causing your system to become sluggish. Referring to the KB article in Step 4 above, click the %CPU column heading to sort it by percent CPU load. If the numbers at the top of the column are zero or close to it, click the same column heading again to reverse the sort order. Higher numbers mean your CPU is working harder on that process than those with lower numbers. Identify these processes and see if you can correlate your spinning "wait cursor" appearance to them.

Good news so far, you have enough memory and there is nothing that appears to be bogging you down.

Next, find your original system install DVD. Insert it then restart your computer using  > Restart... As soon as you hear the startup chime press and hold the D key on your keyboard.

This will start Apple Hardware Test. Let it run all its tests to determine nothing is wrong with your hardware. If it reports anything other than "no problems found" then quit Apple Hardware Test and restart the computer.

This time press and hold the C key. This will cause the computer to start with your DVD instead of the internal hard disk. It will take longer than normal.

When it finishes you will have the "install Mac OS X" screen. Ignore it for now - select Utilities from the menu, and select Disk Utility. When it starts you will see your internal hard disk on the left column (it's a grey box). Select it and then click the "repair disk" button at the lower right. It will take only a few seconds. Then select the disk below and to the right of the first one - it is probably named "Macintosh HD" and otherwise looks the same as the first. Click "repair disk" again. This may take a few minutes.

Record any problems it found - it will be red text followed by green text if anything was repaired.

When you are finished you can quit Disk Utility and then Restart from the menu. Restart your computer normally, eject the DVD and put it back in a safe place.

Let me know what your results are.

No problem, no waste of time at all. Restarting your computer is always a good first step, sometimes it fixes things like this.

Bookmark this thread so that you can refer to it should it happen again. Here is another place to start should something inexplicable happen: Isolating issues in Mac OS X

The fact the slowdowns occur on your account and not hers is a very helpful clue. Clearly there is a process running on yours that is taking too much of your system's resources.

Diagnosing such things is time-consuming. I would use Activity Monitor to identify any obvious culprits:

Identifying resource hogs and other tips: Using Activity Monitor to read System Memory and determine how much RAM is being used

If nothing is immediately obvious, you could always simply create a new user account, configure all your preferences, copy all your documents (via the Shared user folder), establish that the new account works well, and eventually abandon the old one. You could then rename the new one with the same name you had been accustomed to using.

It is sort of a drastic measure, just one to keep in back of your mind as an alternative should you decide such time-consuming troubleshooting isn't your idea of fun.

Simple would be making sure your system is up to date with Software Update.

Also check your "login items" in System Preferences > Users & Groups. Select your account and then select "login items". These are specific to your account and could explain the difference between yours and your daughter's.

It is difficult to surmise what the problem could be since you originally said that the slowdowns occur on "most applications".

Other than that you could re-read Isolating issues in Mac OS X for a cursory review of what you may have already may have done. Perhaps something was overlooked.

... Turns out the culprit was my wireless keyboard and mouse.

That's odd since I imagine that those devices would have affected both user accounts in the same manner.

If they are not Apple Bluetooth devices then check with their manufacturer for a possible driver update.

John - I'm having a similar issue, it shows 41 GB pages in and 20 GB pages out. I only have 4GB of memory and my iMac is 5 years old. It shows I have 35MB to 100 MB of free memory as I'm watching the Activity Monitor. It's showing 3.81 GB used out of my 4GB memory (I have Power point open, firefox, email, calendar, itunes, Xcel). Is it time for a new computer?

You would benefit from more memory. A 2008 model iMac can accept as much as 6 GB. Install all you can.