My primary default Gateway shows as using DHCP

So, for some unknown reason, your workstations that were working fine before now are getting a Gateway of IN ADDITION to the proper Gateway, but the default is so they can’t get online.

  1. Get to a DOS prompt as an Administrator
  2. Type route delete and hit enter
  3. Type ipconfig /release and hit enter
  4. Type ipconfig /renew and hit enter

It may be the Bonjour service  causing this.  To stop it, use msconfig to stop it from running at startup.

Hope this helps