A computer was getting the error message “the trust relationship between the workstation and the domain failed” when trying to log in.  Normally, the fix is to log on as the local admin and unjoin and rejoin the domain; however, in this case, the person did not know the local admin password. [more]

The solution was to disconnect from the network and then log in using cached domain admin credentials.  After logging in as the domain admin, we reset the local admin password, reconnect to the network, unjoined from the domain, logged on as the local administrators, and then rejoined the domain.