I had a customer IT Admin call in saying that they had been trying to login to a Windows 7 laptop that had not been in use for a while and the employee was no longer there.  They kept getting a message when trying to logon that said “the trust relationship between this workstation and primary domain failed”.   When trying to login as the local Administrator account, it said that the account was disabled.

By default, Windows 7 disables the local Administrator account.  The laptop was encrypted, so resetting any passwords by means of a third party password recovery disk could cause the data to be irretrievable.  The IT person had removed the PC from active directory without unjoining the domain, so I could not troubleshoot resetting the computer account.  [more]

After some research, I found that you can boot the system with the network cable unplugged and login with cached network credentials.  The admin was able to login, plug in the network cable, then unjoin and rejoin the domain.  After a reboot, the PC could login to the domain normally.