Same thing here, and after restart I get a message: "Windows has recovered from an unexpected error".When I click for more details it says it's BSOD (Blue Screen of Death)...this happens approximately once or twice a day.
System Specs:
Windows 7 Professional x86
Intel Core 2 Duo E7400 @ 2.80 GHz
Asus P5Q SE
4.00 GB of RAM
Asus EAH4830 512MB (Catalyst 10.5)