New errors creating log files on long-running server

I have a GW7.0.3 - Netware 6.5SP7 - server which had been running just
fine until today, which is also the DHCP server for the (remote) site.
The initial error today was "Cannot update NDS against an entry within
subnet container: dhcp_subnet.Portland.Air." Users were unable to log in
this morning & the primary server seemed hung, but restarting the
primary server (not the GW/DHCP server) seemed to resolve things, and I
thought perhaps just communications had been lost between the servers &
was resolved.

But now the POA and the MTA are showing errors creating the log files.
Things seem to be running otherwise, and there are no errors in the
error log & nothing flagged in the health log, but on the POA I get
"Error creating log file" and then "Disk logging turned off", and on the
MTA I get "LOG: Logging: File Create Error - Disk Logging Turned Off".

Messages are being routed properly, and no disk errors are showing on
the server, so I'm a bit at a loss as to where to start with this nor
why the error has come up. Restarting the POA and MTA does not help,
and I do plan to restart the server when someone is on-site tomorrow,
but I'm not sure how this will help at all.

Any insights or suggestions? The server got new memory about 8 days ago
but was running without errors since, until this morning.

Thanks.