Unable to login to XP

[Sully]

I have a computer at work that I'm not able to logon to when it's booted up with the network cable attached. If I unplug the network cable, boot up the pc, I can log in.

These are the two messages that I get when I try to login:

The system cannot log you on due to the following error:

Invalid access to memory location

and

The system could not log you on. The server authenticating you reported an error (0xC00000BB).


What the heck is causing this? How do I fix it?

Last resort is to reload XP, but a user has a lot of stuff on here that I can't lose.

[Mike]

So with the network cable unplugged it'll log in without errors? Is this a member of a domain?