The first thing I would do is select from the boot menu "Disable automatic restart on system failure" and then boot up. It should give a BSOD.
This is a Windows issue. If you have a Windows XP CD and can't disable automatic reboot, do a repair install. This will preserve your data. If you have important data on it but don't have a Windows XP CD, get an external enclosure and get your data off with another computer. Then run the recovery CDs or use the recovery partition.
Laptop Recovery Instructions