Bad iMac Troubles

I've had this iMac for about 7-8 months now. It is a Rev.B (specs on the left). After a reboot or start up, it runs fine, for about a few minutes. After that all I can run is like Safari. Any program that I try to launch freezes and crashes my computer. I then can not shut down the computer even manually and have to unplug it from the wall.

Any thoughts?

Start here:

http://www.mac-forums.com/forums/showthread.php?t=5284

next time you restart make sure to run all updates.
repair your permissions, zap your pram etcetcetc.....check the osx troubleshooting thread for the things you can do

worse comes to worse it sounds like you may need to do an archive and install
-chris

oh. i have reinstalled on several occations and when i do, it works fine UNTIL i install all the programs i use.