I have a relatively new machine (November 2009) with Windows 7 x64 Home Premium. Since beginning of January, I experience more and more frequent black screen of death. I could not associate to any software firmly, but it did crash relatively frequently during video playback, Google Earth, and flash movies within browser. The frequency of crashes increasing, now it make no more sense to start playing a DVD.
I restored the system from a backup image from early November when the computer was still rock solid. After restore plus installing Nod32 anti virus (I bought the AV after the backup) and the latest Windows Update patches, the computer crashed within an hour.
My guess is that the issue is caused by HW failure. I ran a memory tester all night, but it did not find any errors. Due to the frequent crashes during video/GE, I have suspicion towards the video card. Can you recommend any testing/curing solution?
HW: Desktop M5812/Intel i5 processor/NVidia Geforce 220/6GB RAM
EDIT: I have replaced the video card with another borrowed NVIDIA card, and DVD playback is as smooth as butter. I took a look at the old card and I recognized that the heat sink is completely jammed with dust, so cooling certainly was not going very well. I cleansed it and placed the old card back. It seems like it works again.
EDIT2: After vacuuming the original videocard, the computer is running very stable now for several days. Thank you for all the contributions!