Now I have been in safe mode, and I couldn't make the error occur, even if I know how to do it. I open two instances of explorer and move some files, close both explorers and try to open another program and it use to come up with an error message, but not this time.
I have no other problems with my computer, and it doesn't do this evry time, but very often.
A good thing about Vista, though, safe mode doesn't make a mess of my desktop like W2K did.
CPU temp. after several hours in use: 41°C - 104°F
MB: XFX MB-N680-ILT9
chipset: nVidia nForce 680i-LT-SLI
CPU: Intel Core2Duo E6600 2,4GHz
RAM: Corsair XMS2, in all 4GB
Videocard: nVidia GeForce 8600T
PS: Hiper Modular 580W