What to do if you can't login to a public computer
Check the network cable -- to login you need a network connection.
Reboot - public computers revert to a known good setup after rebooting.
"Trust relationship has failed" -- it means that the computer needs to be removed and readded to our domain. Check the network cable. Try rebooting it, if that doesn't work, contact the Helpdesk and give them the error message verbatim. The helpdesk will arrange for the lab team to fix the problem.