Problem with Win2000 and Network-Share. Help!

We have an Windows-2000 AD-Domain. On the Windows 2000 Server there
are some network shares. These are mapped on the clients.
There is enough space free on this Server.
Clients are Win2000 Prof and WinXP Prof. We save our user profiles on
the server.

On one Client (Win2000) there is a strange problem that the user
cannot save files to a network share because of the client thinking
there is no space left. An Error telling this is raised.
The explorer shows a drive size of 1GB (the drive is much bigger) and
some KB (these values vary) free.

If I unmap all drives (net use * /d) from another user account
(because of the server-saved profiles) and reboot it works again for
some hours.

I tried to...
.... reinstall the computer - same problem
.... deleted the user profile on server and client (after backup of
course) - same problem

I have found another post which could be related to this problem - but
it doesn't help:

Next - if noone has a solution - i will backup all user files and
outlook and re-create the user account.

Strange problem - isn't it?

Thanks in advance
Florian Lagg (