Windows My Computer Won't Start!!

I had just installed a http://www.crazypc.com/Merchant2/merchant.mv?Screen=PROD&Product_Code=50071 on top of my amd 3000+. I had to take the mobo completely out of the case and detach all cables to screw in the supports under the mobo. After about an hour of that and setting it up and finally putting all the cables and screws back in I turned it on with the case open to make sure all the fans were running. All fine. So I opened my asus probe and the cpu temp read 32C!! Eventually it went up to 52C and I thought it was because I didn't tighten the screws down onto the processor enough. So I opened the case, made the screws more snug and closed it up. When I turned it on it first showed the bios screen (normal) then it showed the via screen (normal) then it went blank. I cannont figure this out. Please help me, I don't want to get ripped off at the computer repair shop AGAIN.

EDIT: Also, when I hold delete to enter the bios it works, but then I none of the keyboard keys do anything. I know it doesn't freeze because the bar at the top of the bios screen is moving.

 

Please? Reply? Someone? Anyone?

 

have you:
tried clearing the CMOS.
Putting the old heat sink back see if it works,
Check for any shorts on the standoffs (motherboard mounting points).
try taking the cpu out put it back, to make shore its in well.
try changing the hard drive cable.