[mbb1i]

I have a very weird problem with my Mac Pro. My computer will run fine for a while but then it will start acting strange. The mouse will start to move sluggishly and not click things, but only for a few seconds, then it will click and move, then it won't and so on. It doesn't stop there. After some more time, my mouse will stop highlighting. What I mean by that is that when I click on a menu bar option and then drag the mouse over the new options that appear, the mouse won't highlight the options in blue like it's supposed to, they just stay grey. Also, when I drag the mouse over the dock, it doesn't show the names of the apps above the icon. Also, when I drag the mouse over a link in safari, they link won't highlight. It's not the mouse, I have tried three other mice.

FYI, I've opened up the computer and given it a good cleaning. I have SMC Fan Control and it keeps the computer very cool, so it's not overheating. If you need to know anything else, please ask. Thank you.

[Big Mac]

Sorry you're experiencing that problem. Try running the Hardware Test on your system disc. Those symptoms sound like bad RAM to me.

[mbb1i]

I ran the hardware test and it said everything was fine.

[reader50]

I can think of a couple problems to look for. Open up Activity Monitor, with all processes sorted by CPU usage. Leave it open. The next time your mouse becomes sluggish, look over and see if another process is hogging CPU.

Alternatively, a graphics card warming up might cause display issues. Bad RAM typically causes crashes. Overheating VRAM usually produces random pixels / lines on the display. Neither symptom matches what you report, but a hot GPU might. You could install Temperature Monitor, use it to monitor the GPU temp.

OS corruption could also cause these symptoms, except I'd expect them to be corrupted full-time. ie - menu / Dock label problems from first boot. Not kicking in after awhile. If you have another partition or drive available, you could do an OS install on that, and use it for a few hours. If this is caused by a hardware problem, the problem should manifest in the other install too.

hmm ... thought on side. How much RAM do you have? Are you running a lot of apps in the factory minimum, with a nearly-full hard drive? A memory crunch situation could also cause these kinds of problems

[mbb1i]

Everything seems fine with the temps. I have 5GB of ram. I have only half of my 500GB hard drive filled. The problem doesn't only happen when I have many apps running. I'm usually just running safari and mail and it still happens.