I have one of these that powers up, with fans going full. But no video display or bootup. E.g bootable floppy or dvd burner or HD does not bootup. The lights on the dvd do blink. But nothing will boot. The unit is stock with onboard video & 2 x 256 meg sticks of ram (which are fine tested in another pc) I've reset the bios including removing the battery. Still no display any ideas?