IMac freezing intermittently--every few minutes. How can I fix this?
It's very unlikely you downloaded something or broke everything with one download. Also - with at least 4 things not working well - please protect your pictures, emails just in case it's a hardware failure.
When only one thing is broken - it's often worthwhile to poke, learn, understand what broke and look for a fix of that one issue.
For any group of three or more problems, there's one solution that always works (and often saves a lot of time):
- Back up anything you can't afford to loose and get someone who is a bit tech savvy to verify you have a workable backup that you can restore if needed.
- Erase the mac and install just a clean system from the media that came with the mac.
This will quickly let you know if the hardware has failed. It will also solve nearly all software issues. Once you have surfed the web, made sure it is reliable, then you can run updates, restore your personal files and get on knowing it was just some corruption of the software.
Don't feel bad getting help from someone (even paid) if your savvy is for things other than a computer. A good tech can erase and install Mac OS X in 10 to 30 minutes. A good tech might take 4 hours to 4 days to pick apart all the things that could be wrong and tell you what happened. With multiple issues, it's hard to tell what was the root cause and what was just a subsequent failure.
It's often so much easier and efficient to just clean up the mess, start fresh, and keep an eye for any sign of the problems recurring. You will then have better data on the problem. You will also have a backup of your important files.
Since your computer can't tell if it has enough memory to run, (or is truly out of space) you can't really trust itself to fix itself which is why I jumped right to backup / restore for anyone on a situation as you describe. Also, if you were to determine exactly what broke, and did the fixes right, if it freezes or doesn't complete your fix - you will still be in the same badly working situation.
Best of luck - some good people have made answers with great advice here as to what could be wrong. I wanted to weigh in with a different sort of advice since no-one (you included) had mentioned protecting your data files.
You should check the Console logs.
My computer displayed these exact symptoms. The console logs displayed this error:
kernel[0]: disk0s2: I/O error
After reformatting the hard drive and locking out bad sectors, they went away for a time. Alas, they came back, and it seems I'll have to replace the hard drive which is likely failing.
In your particular case, you may be able to correlate the times of "stuttering" with errors in the log and determine what is causing the freezing. Good luck.
If this is something that's now happening regularly then it's likely a failed hardware component (which can get expensive if you don't have AppleCare (Pro Tip: go buy AppleCare and register your computer NOW (unless your Mac is more than 3 years old))). But it could easily simply be a corrupted filesystem. Boot from your Mac OS X install disk and run Disk Utility. Select your hard disk and run Repair on it.
If this is something that doesn't happen frequently (i.e., it happens several times in a row, but long intervals where it doesn't happen at all) then it could be a heat issue (you can enjoy the humor in heat causing your Mac to freeze). There are some temperature monitors that can run in the menu bar. Install one of them and keep an eye on it. If anything gets close to above about 175° F then it's too hot. Also, if the ambient temperature in the room your Mac is in is above 95° F it's likely that the internal temp of your Mac is too hot. Turn on the AC, buy some and point them at it, etc. Do anything you can to cool it down.
Also be aware that prolonged excessive heat can cause serious and permanent damage to your system.
But if it's not heat, then it's probably hardware. Backup your Home directory and take it to Apple.
Boot from the Restore DVD and check the drive. When all is fine create a new user and see if the problem exsist while logged in with that new (clean) User.
Case Problem gone? Softwareproblem. Time for Try and Error: Move all Prefs and Application Support items out of the Library of the Account and see if the problem is gone. Move the items back in groups till you know what item/pref cause the freezes. Basically you need to find the difference between the working user and the freezing user.
Case Problem not gone? What Bahamat said. Take it to repair.