Thanks for the info, Distant_Horizon.
The link in your message isn't working, so I wasn't able to check that out. What is this beta patch you speak of? We used "Windows XP Security Patch: Buffer Overrun In RPC Interface Could Allow Code Execution" and it stopped the reboots.
Also, in regards to firewalls, I think most people will not go out and buy a hardware firewall. A software firewall like Zone Alarm is better than none!