RAS Error 745: Missing essential file

Using RAS 1.3 on Win95 workstation with 3Com/USR 56k v.90 external modem. Dial, NT server 4.0 answers, negotiation, connection, then Dial-up Networking message box displays: Error 745: an essential file is missing. Reinstall Dial-up Networking. I’ve done this, but no joy. I suspect this is a spurious msg, not relating to what is happening. Nothing shows in the NT event log on the server. The modem log shows remote modem hangs up after data compression comes on. Any ideas?