Cannot access VPN, error 650

I receive error 650 after the ‘Verifying username and password” step when trying to connect to a VPN on an NT 4 server from both an NT 4 workstation client and a Windows Me client. Both connections worked the week before. The NetAdmin added a local workstation to the network at the office but assured me that it should not have affected the VPN in any way. The NT workstation error message includes a fail code 0x14. The NetAdmin had me reinstall service pack 4 on my NT machine (didn’t help). Nothing else has been changed on either of my home machines.