SERVER3 has been in place for about a year with no problems. Suddenly,
users are unable to attach. Users with connections continuing working with
no problem.

Reboot server, or simply unload/load ds.nlm and functionality returns for
about 45 minutes. Problem reoccurs consistently.

When problem occurs, the Connection List in Monitor shows no usernames
next to the connections -they simply disappear.
When problem occurs, utilization on Processor 0 holds at 100% - Busiest
processes are Serverxx belonging to SERVER.EXE.
Unload/Reload DS.NLM and utilization drops to 0% - 5% and functionality
returns for less than an hour, then it all happens again.

Server "SERVER3"
Netware 6.5 w/SP6
DS Version 10553.73
Server does not hold a replica.
Other servers w/replicas respond to pings and are connected to same switch.
No problems shown in dstrace on servers with replicas. Everything looks in
sync w/no errors
Not ABENDing.

I have just tried installing the latest ftf for DS with no change.

Any ideas?