Sometimes you’ll find that for any one of a multitude of reasons, a workstation’s computer account becomes locked or somehow otherwise disconnected from the actual workstation (say, if a machine with the same name joins the network, or if it’s been offline for a very long time). When you try to log on to the domain you’ll get a message that states:
“the trust relationship between this workstation and the primary domain failed”
Now, what I would normally do in this situation is un-join and re-join the workstation to the domain, which works, but creates a new SID (Security Identifier) and can therefore break existing trusts in the domain with that machine, and of course it requires a reboot. So if you don’t want to reboot, and you don’t want to break existing trusts, do this:
Use netdom.exe in a command prompt to reset the password for the machine account, from the machine with the trust problem.
netdom.exe resetpwd /s:<server> /ud:<user> /pd:*
<server> = a domain controller in the joined domain
<user> = DOMAIN\User format with rights to change the computer password
* = the domain user password
That should do it, in *most* cases.