weird runtime errors in xp causing crashes

[bg12]

I've been having these very strange runtime errors lately; I'm not really sure how to describe them but I'll try my best. A few hours after a restart some program will have a virtual basic C++ runtime error (the program varies and I haven't been able to read what the runtime error is), and then the graphics on my desktop go haywire. The top bar of my internet browser disappears, text in various places (like "start" in the start button) vanishes or becomes an underscore, and then I just have to shut things down and restart. If I mouse over a lost top bar or icon it will come back, but no programs work after this cascade begins. I've done virus and spyware searches that have come up empty. Anyone have a clue what this could be? I tried to look this up but I'm not really sure how to google these symptoms.

 

[bg12]

bump - anyone have any ideas?