Access is Denied Event 5722

A client has an XP Pro System in an SBS2003 domain. The user decided to change
the time on the system such that it became out of synch with the domain.
The user could then not log on to the domain. Another vendor fixed the
obvious issue, however, as a result their backup (veritas backup exec) cannot
access the xp system, and the system cannot be accessed via remote desktop.
The backup messages are "authentication failed on connection to the server"
and "access is denied to the remote agent". The backup uses the
administrator account for th backup.

The system log contains event 5722 "session setup for the computer xxx
failed to authenticate. The name of the account in the security database is
xxx$. The following error occurred: Access is denied." This is obsiously
the main issue however, this is new territory for me. It appears there is a
mismatch of the computer account name in the security DB and the machine
account name. How do I go about getting them to match? Would removing the
system from the domain and rejoining repair this issue? Thanks for any and
all help.