1. Stop the automatic restart to get information from the Blue Screen of Death (BSOD).
Tap the F8 function key once or twice a second as you reboot the machine. The Windows Advanced Options menu should appear. Use the up/down arrow keys to select the "Disable automatic restart on system failure" and hit Enter. Hopefully the machine will stop on the BSOD.
2. BSOD. Record and post back with the "exact" error message text and/or numbers plus any offending software module it might name. A google search on these text strings or substrings sometimes provides problem resolution.
3. What service pack level of Windows XP Home are you operating at, if known? None, SP1, SP2, SP3?