Hi Everyone,
I know this is years old now but I had the same thing hapen to me on my Windows 2008 R2 Server.
I couldn't even boot from the Original 2008 DVD, It would get up to the Moving Graphic Windows Logo Screen and then the system would just restart at the Cold boot BIOS screen. I checked all the BIOS settings and couldn't find anything that even looked like a problem. (This machine is an old Dell 6400 server and the BIOS is really simple).
Different from what the other users here have reported I have a RAID Array and ran a full diagnostic on the raid set and after hours of looking it couldn't find any problems. At this stage I still thought it is probably a corrupted file which is why I tried to boot from the install disk.
Just for fun I tried booting from an old XP disk into the setup routine and that worked OK.
Of course I didn't actually install XP as I was still hoping to save the previous system.
Again just for fun I popped out my SCSI card and re-seated it again. The SCSI card doesn't run much more than the DVD drive these days as the RAID controller is completely separate.
Much to my disbelief the machine booted and is now running perfectly.
Who would have thought :)
I hope this post helps someone else dealing with this obscure problem.
Good Luck
David