Failed NT4 Logon

Since there is no Safe Mode in NT 4.0, how can one sign on to local computer when authentication fails (even though user account & password are the correct ones)? While attempting to sign on to Domain, immediately an error message comes up that thetrust relationship has been broken between domains for this computer account. But, the system really never even tries to authenticate user/workstation. I suspect maybe a bad NIC??? But need to access the local machine to check. Note: Local Administrator account doesn’t work either (unknown password).