Since last Thurs I've had a problem with a Netware 6.0 sp3 server randomly

It's a Dell Poweredge 2500.
1 Gig of Ram
Sp3 (no patches after sp3 as it's been running fine until now)
Raid 5

I ran DELL diags on the machine and they all passed.

I turned off autorecovery after abend but that didn't help.

There is nothing in the logs regarding any problems with the server.
Actually the server has been running fine for over 3 years.

I was hoping it was a hardware problem but the diags that I recieved from
DELL this morning didn't find anything wrong.

Any ideas.