I recently worked on a problem where some PCs at a customer site were not able to login. I checked the server and it showed many group-policy errors in the App OS log listing the 'GPT.INI' file.  I also noticed the group-policy mgmt console was not able to open any GPOs - said there was a rights error.  'Net View' only listed the server and no workstations.  I had one of the users experiencing the problem reboot and her system said no domain controller was available.  Further research indicated that 5 minutes after last server reboot, these services crashed:

  • TCPIP Netbios Helper
  • Alerter
  • Windows Time
  • Webclient
  • WinHTTP web-proxy auto-discovery

The Windows Time was able to restart itself, all others were stopped. Restarting the netbios helper service appears to fix the main problem (all PCs came back in the net view list), including the group policy App errors and mgmt console issues.  More research on the Internet indicated others had problems with the webclient service killing the netbios helper on Server 2003 and that SBS was supposed to have the 'webclient' service disabled by default due to security issues