When you attempt to establish a VPN connection to a VPN server, you receive:

Error 781
Encryption failed because no valid certificate was found.

This can occur on a new connection or on one that previously worked.

The error is produced because the connection is incomplete. You should:

1. Verify basic network connectivity between the client and the server.

2. Make sure that you have name resolution between the client and the server.

3. Use the Networking and TCP/IP troubleshooter in the Windows 2000 Help.

See Q169790 - How to Troubleshoot Basic TCP/IP Problems in Windows NT 4.0.