check disc on the harddrive (right click the c drive / properties / tools tab / error checking... check now - check both boxes.... you'll have to reboot to run it.
It is the IDE Hard Disk Write Error. You can Go to the drive manufacturers web site and download the diagnostic software, that should tell you the problems. You should also check HDD connections, and see cables are connected properly, make sure the bios is should also detect the HDD. In that case the IDE HDD needs to be replaced.
This can happen, when the NT system is not in a proper state. Best thing is, if you boot the system with ubuntu, mount all drives and shut it down correctly. Propably the error is gone when you reboot now with xp. To get a bootable ubuntu cd you can get an image at the ubuntu community.