We are looking after a Server running SBS 2008 with 9 client PC's running XP pro and 7 users (plus an admin account). All of a sudden, we seem to have a problem getting users logged on. If the users have logged in using a client PC they have used before, they get an error that starts 'Windows cannot locate the server copy of your roaming profile and is attempting to log in with your local profile' and ends 'The system detected a possible attempt to compromise security. Please ensure that you can contact the server that authenticated you.'.
If users try to login using a client PC they have never used before, they get the error 'The system cannot log you in now because the domain <domain> is not available'.
I have tried creating a new user in SBS 2008, but get the same error (2nd error) when trying to login with any of the client PC's using the new user account. I have also turned removed the roaming profile link from each user account in the Server Manager but still get the first error when trying to login using any existing user on a PC they have previously used. It's as if the client PC's can no longer see the server. However, when you are logged in to any of the client PC's (using a local profile), you are able to browse the shared folders on the server and print to any shared printer attached to the server. Any ideas?