You problem is oplocking, and is caused in your case by too old clients.
Either update them *all* to 483SP3, or disable oplocking altogether on
the server, by doing:
set client file caching enabled=off
set level 2 oplocks enabled=off
CU,
--
Massimo Rosen
Novell Support Connection Sysop
No emails please!
http://www.cfc-it.de
It doesn't necessarily require a reboot, but only new connections will
be affected, so a reboot is the most safe way to ensure no old client
connections still have the problem.
BTW, 4.83SP3 is where all Novell files are.
http://support.novell.com/cgi-bin/search/searchtid.cgi?/2968055.htm