[Buran]

I'm going crazy here. One of the original-model 15" flatpanel iMacs (with superdrive) I work with is acting rather odd. A lot of the time it will not start up, and at times it will randomly lock in the middle of something.

Odd patterns of red dots appear that follow the cursor (which is the only thing still functioning when the machine locks) -- they seem to often be arranged in several columns ...

I've tried switching RAM, unplugging everything, wiping and reformatting and reinstalling the OS (my boss won't let me boot primarily into X yet so I installed 9), it will either freeze after the happy mac (stops at grey screen) or at the desktop (partially drawn finder windows appear before the machine hangs).

[gto47]

This sounds like a hardware problem to me, the logic board will most likely need to be replaced. Contact apple or your local apple certified dealer about having it repaired.