Domain Settings

I have a problem with Windows 9* & Windows ME, system
where as I need to change the domain name.

we currently have 2 domain names on the network, the
first being:

domain1
and the second being:
domain1-de
for use ín our German office. but one of the computers in
the German office defaults to domain1 but this needs to
be changed to domain1-de, when I chamge this under
network setting then computer reboots and all is ok. but
when someone then logs on then logs off the domain has
defaulted back to domain1

does anyone have any ideas how to fix this problem. any
help would be much appreciated.

Regards

Adam.