samba - Oct 2002 - w2k hangs while access samba

another question,

w2k clients hangs temporary while working.
If you don't access a samba share for a while, it will freeze the whole 
network neighbourhood for a while, after I try to open an other file.
I notice these on several w2k clients, not on w98 clients, in several 
networks.
Has anybody an idea for this problem?

regards
Thomas