When RAS Fails -- Connection Has Worked Before:
Internal - Service running on client and server? Callback number changed?, Reinstalled OS w/o RAS? Modem running?
External - telephone lines between client and server functional?, ISDN telephone company's hub working?
Check Audit Records in the Event Viewer:
- Audit: normal event - successful, failed, both
- Warning: irregular event not affecting system function
- Error: failed event or network error