Some things to try:

Make the following Client settings (at the problem workstations):
use extended file handles = on
close behind ticks = 0
opportunistic locking = off
File Caching Enabled=OFF
Delay Write =OFF
End Of Job =ON
Cache Writes = OFF
Hold Files = ON
True Commit = ON

There is a problem in the opportunistic locking code in FILESYS.NLM. This causes client requests to stack up waiting to get access to the volume. Install the correct patch:
FLSYSFT3.EXE for Netware 5.1 sp2a. or
FLSYSFT4.EXE for a Netware 5.1 SP3.

Ensure the MAXIMUM FILE LOCKS PER CONNECTION is set at the server for the number of file locks required by the application and client (raise this number).

If there are any virus scanning software on the machine like Norton or McAfee, remove them temporarily from the workstation and reboot it and see if they might have been causing the problem.

Since these problems have occurred numerous times, you should cleanly uninstall and reinstall the novell client before testing everything else:
1. Run UNC32.EXE to uninstall the client on Windows 95/98.
2. Delete the C:\NOVELL directory.
3. Reinstall the LATEST NOVELL client from scratch.

Check the Half Vs. Full Duplex duplex settings on the network cards.