Okay, Yeah I know not much of you may know about this topic or what to do...
When I boot my computer up, bois and everything loads, As for me I have 3 OS installed, XP, Vista and Windows 7. As soon as I select one of the windows it goes to the boot screen for it, then cuts right off :(. What can cause that :'(
Sorry to tell you this, but you computer has cancer. But really you might have some corrupted files or something like that. Try using a live CD to make sure it's not the computer it self.
I tried, and it cut off on that too :(