User profiles change

Any know why Windows 2000 would create a new user profile?
I have users that have all their stuff 'missing' lately. When they are logging on to our domain via W2k they are getting a new profile outta the blue.
Their old profile is like: username the new one created is username.domain.
These people have been on the domain forever, so why does it feel the need to create a new profile?

 

If the client can't contact the server, but can resolve username and password, this would happen.

Can these users, later on, ping or access services from the server?

 

Why is that? if I take my laptop off the domain & bring it home, I can still logon with cache creds. & it doesnt create a new profile. It has happened twice in the past month maybe. I know corp. just pushed out some patches...