I got the same problem on my very freshly installed Windows 2003.
SVCHOST.EXE crashes, whitch results in a reboot.
I know I can cancel the shutdown by shutdown /a and I know I can disable the reboting by setting it in the RPC service.
The question is not how to prevent the rebooting, but how the hell can I fix this problem?
I've installed Win2k3, and reinstalled it to be sure that it wasn't Win2k3. also tried several virus scanners to be sure it wasn't a virus.
My system is always connected to Internet via a LAN & router.
Faulting application svchost.exe, version 5.2.3790.0, faulting module rpcss.dll, version 5.2.3790.0, fault address 0x0002eb3c.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.