My friend has an old computer i gave him with Win 98 on it. It was working fine whe he tried to install a new game on it, and after it finished he hit the option to register later. It gave them the black screen of death where it would white out once and a while. When it was turned off and on again, it booted reading 'disk boot failure.' Any ideas?

I ha a similar problem where it woulf not see the Hard Drive. Turned out to be the motherboard battery. It would stop before window and say HD not detected. press F to continue or F2 to enter setup.
Battery fixed it.