I too have a PC running Vista on a mixed Windows network with Windows 2000
servers. My user logged in after an absence of two weeks, he thinks he may
have forgotten his password and got it wrong "a couple of times" and now is
getting a message to say that the "trust relationship has broken down".
There is a work round which suggests that the user unplugs the network cable,
logs on to the computer and then plugs the network cable in - this apparently
then connects to the network - and does so in our particular case.
I had intended to remove the computer from the domain - but I understand
that when a PC is added to a domain the local administrator account is
disabled - and of course I won't be able to log in as domain administrator -
so I am not sure what to do next! My inclination is to log on to the computer
while it is on the domain and remove it from the domain - having first
reactivated the Local adminstrator account - then delete the account on the
server - then join the PC into the domain again. Am going to try to find out
more before I do so though.