Hung logoff with roaming profile on Vista 5536

I was testing a roaming profile on Vista 5536, and with this enabled, a
couple of times during logoff, the system hung at the 'Logging off...'
screen. The system continued to run, and to give feedback that it was
working on logging off the user, but after hours of waiting, it never
finished. With the firewall on, and no kernel debugger attached, that left
no option but to uncleanly power the machine off, which I really don't like
to do.

My question is: is there any way to interrupt the logon/logoff process from
the console, so that an Administrator can log onto a new session and find
out what's wrong (or at least terminate the hung session)? I suppose
allowing remote access is always a possibility, but that requires reducing
the firewall settings, which I'd prefer not to do on a roaming laptop. At
the least, I'd like an on-screen 'power' button to cleanly shut down the
system (if this is possible). For now, I'll change the power button from
'sleep' to 'shut down', and see if that works.

Has anyone else seen this problem with roaming profiles, or had better
success with them on Vista 5536?