crash hard

I put togetheir a P4 1.9 gig on a D450WN intel MB.
I had WINXP with a 60gigHD. and AGP Card. THe system worked fine for about two weeks. I also add a KVM switch so I can acess two PC with two different OS. One mornning I turn onthe monitor and the screen was frozen. I could not reboot. I had to do a hard boot. I first time it went to the default P4 Screen and stopped. The second time it went dead. No picture. All the fans start up. No Post NO HD.