sometimes BIOS and the system settings mess up especially when there's a slight surge or something... this may have no affect with your lights, and the computer might not even go blank, but some of the settings get screwed... (BIOS)... twice it's happened to me, and I had to reset the BIOS, cause it disabled my COM ports and all that...
i'd say before you do anything, take your computer to get backed up, or do it yourself (burn CDs or whatever) or if you have one of those large IOMEGA or whatever drives, then back up your disk 100%, (i.e. copy the system files, and everything, as set up... so you've got a 'ghost' of your computer, to be sure you don't miss anything, and it may come in handy later) then take your computer in to get repaired... it could just be some BIOS conflict...