Beware the new June 7 beta refresh of 4.91sp4 posted on beta.novell.com.
There appears to be a problem with the SRVLOC service not starting upon
bootup. This causes the NetwareWorkstation service to also fail to start.
If you login Workstation Only, then go to command prompt and type "net start
srvloc" then "net start netwareworkstation", this seems to get things
working again. This was tested on machines running the previous beta from
March on Windows XPsp2 workstations.

Errors reported in Event Viewer:
The Novell Service Location service failed to start due to the following
error:
A device attached to the system is not functioning.

The Novell Client for Windows service depends on the Novell Service Location
service which failed to start because of the following error:
A device attached to the system is not functioning.