I've got a friend with a weird problem. When he starts his computer the screen is completely black until the computer is completely started. So the screen is black until it suddenly shows the Windows desktop. He said that this is happening since a technical service repaired his computer, but that repair is not now in warranty.

Recently the computer stopped working, but as the screen is black he cannot access to BIOS or start in safe mode (by pressing F8). When he inserts the Windows Vista DVD the system doesn't boot from DVD (it mustn't be configured in this way in the BIOS). Maybe there´s a problem with the hardware (maybe the graphic card)?

Can anyone explain a reason why the screen is black during start-up? Any idea of what to do with the computer to restore it?