My computer (XP) continuously re-boots.It comes up normally, but then the screen goes blank and the computer re-boots itself as if I purposely hit the re-start! It has rendered the system totally useless. I tried to boot from the XP CD to repair or recover, but as it goes through the motions to read the system, the same re-boot occurs. I have tried to boot up in safe mode with the same result. Is there a fix? Help please!