The trust relationship between the workstation and the primary domain failed.

When you get this error at a VMware VM (when you restore an old snapshot), you need to drop the association with the domain are remake it. For Windows Server 2008 R2:

1. right-click on the "My Computer" equivalent and pick "Properties"
2. click "Change Settings" at the center far right of the box which appears
3. at the "Computer Name" tab of the set of tab which shows up next, click the "Change..." button
4. you will see a radio button toggle for switching between Domain and Workgroup and you should switch to a bogus Workgroup, just making up a silly name for it
5. enter a username and password for the domain when prompted for something
6. restart
7. go back to where you just were and switch back to the domain
8. log in for real
9. restart again

Do not bother with running "dsa.msc" from the start menu which opens the "Active Directory Users and Computers" tool. I found this in Googling but it didn't help.