I've been running my head into the wall for weeks trying to figure out what's going on with my PC. It's been crashing randomly with a blue screen and a 'machine check exception' error. I've replaced the RAM and gone from on-board sound to a separate sound card thinking there might be an IRQ conflict due to the fact it usually happens when a sound starts playing. Not a specific sound, just a new sound...different one every time, and a sound that has played before. But that's not always what causes the crash, I've yet to pin down a constant in all of my scenarios.
Perhaps related? --> When I leave my PC unattended overnight, if it hasn't rebooted it's extraordinarily slow. Once I get Task Manager up, I have a process running @ 99% CPU Usage. Normally it's msmsgs.exe, and when I end it, the 99% CPU usage jumps to iexplore.exe. If I'm able to terminate that (as the PC is running terribly slow) the 99% CPU usage jumps to explorer.exe.
I am running Norton Anti-V and scans have turned up no viruses. Definitions up-to-date.