Please help with monitor problem! Urgent

[ZPep]

This is really scaring the hell out me.
I just got a computer built that i really like.

Radeon 5770, Athlon II X2 245, Asrock N68-S Mobo, 2GB DDR2 Ram.
Okay.
I was using Sony Vegas 8 Pro video editor that i downloaded.
I was editing my video, all of a sudden my computer restarted!
No signal from monitor.

It gets to the "Start windows normally" screen (Windows XP) and then it crashes and i get No signal!

Please help me. I have switched monitors.
What's wrong?
I'm scared it's a GPU problem because i just got the Radeon 5770 and it's been running for less than 2 weeks!

 

[wassja]

Perhaps the problem lies in windows. Try pressing f8 while the computer starts to enter the "Save mode". If the save mode starts without crashing, then your problems might be software relater - damaged OS or a virus, badly installed driver. reinstalling windows or removing the program/driver/virus would solve it if this is the case. It's a possibility.