When was the last time you cleaned inside the case of your PC?
This CNET video may help;
http://reviews.cnet.com/4520-11319_7-6240575-1.html
Do you see any Blue Screen? (Blue Screen of Death, or BSOD). See if the Event Viewer logs these events. Goto Start > Run, type in eventvwr.msc can click OK. Double click any entry for more information.
Mark
My computer often becomes "Non-responsive", freezes, crashes to desktop and blacks out. This occurs mainly when using the "Flight Simulator" program when one of the above prevents me from continuing. Today it occured while compiling a slideshow in Windows Movie Maker. I have just spent $40 on PCdoc, hoping that it might fix it, but the problem is still there.
Intel Pentium 4
Radeon 9600 graphics card
2gb of RAM

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