Win 98 client disconnected after login to domain on Windows Server 2003

I have this strange problem that a Win 98 client will get disconnected from
the networ (cannot browse any network computers) after successfully login to
a domain on Windows Server 2003. The problem will be solved when I re-login
to the domain again. I have installed directory service client on my Win 98
system. Does anybody have any idea why this is happening?

Also, the Win 98 client cannot access another domain in the network. Meaning
that when I am login to 'sales' domain, I will not be able to access
'project' domain over the company's network. "Access denied" error will be
prompted. I have got no problem at all when using NT4 server for both
encounters.

Any advice for me?

Thanks in advance. Happy new year to all !