NWSBS6 SP5, Dell PE2600, Dual Xeon (HT OFF), 2GB RAM, Perc4, RAID 5.

I had cause to run a DSRepair whilst trying to resolve an NLS issue (I
removed and reinstalled the licences - server and conn). Each time I run
DSRepair - Unattended full repair I get an error message in DSRepair
saying files are missing (can't recall error code, though I don't want to
repeat the process if possible as it makes me feel ill). A message on
the server console appears as below.

pki could not create an nds context (no entries appear in dsrepair log)

The database files lock, then they cannot unlock and the DB is unloaded,
I have to reboot the server to get the DS open again.

I can run a local repair, and do all things in Advanced Options. This is
the only server in the tree and it appears to be operating fine. I
Assume certificates are working as HTTPS connections to the server are
OK. PKIdiag shows no major errors.

Any ideas as to the cause. A DS error like this is likely to keep me
awake at nights.