I have a 2k and an XP machine on a small net. For some unknown reason
recently, the 2k machine seemed to decide it no longer wanted to have
anything to do with the XP machine. However, we've discovered that,
if we reboot the 2k machine, and then during a very specific point in
the bootup process, we attempt to map drives to it from the XP box,
the 2K machine DOES ALLOW IT, but ONLY during that brief 10 or 20
second period, presumably when the 2k machine is partially up enough
to accept connections, but not fully up, when it again disallows

Once we've slipped in with XP and mapped to the 2k, everything works
fine, even after 2k is fully up. We can map additional drives, print,
everything. Only when 2k reboots does it fail again.

Clearly something ends up starting on the 2k which then disallows
connections, but we've removed all firewalls, and can't find anything
else running which might be responsible.

Is there a way to single-step the 2k's bootup such that we can isolate
down to the exact process which is causing the problem?