XP shutsdown after startup

hmmm....if you have the windows xp with you, bootup with it. go into the bios first and change the first boot device to cdrom. then save settings the exit the bios. then the computer should boot to the cd and in the main console, choose repair.

then the computer will ask you for an admin password but if you dont have none, simply hit enter to skip the process. then on C: type in "fixboot" or"fixmbr" without the "". this should only take a second and restart the computer after that. then bootup to windows normally and see if this fixes the problem.

also can you boot into safe mode at all? restart your computer and keep on pressing F8. then when you get to the safe mode menu, select "last good configurations" and see if that fixes the problem.

I dont have the pc with me - its at work. Ill try your suggestion tomorrow. It will boot to safe mode after trying several times and eventually shuts down. Last known good config. yields the same problem. I have managed to get it to start briefly from "last Known" but it shuts down soon after-Itried to retore and it shuts down before I can select a date.

I would go all the way to XP repair, passing the first request for repair and choosing new install, then choosing the next choice of repair ...of course booting to the cd as suggested for mbr fix...doesn't sound like mbr problem.
Out of curiosity are you sure the pc was off? Check bios by tapping F2 after first pushing power button and see how power Management is set up...if by chance power button is set for 4 second delay in PM, change to instant off, and then try booting.