>If the problem doesn't occur with a local logon (I assume local account, rather than domain account) that's a very useful clue. It points to some sort of security/permissions issue. BTW did your test domain user logon have local Admin privileges?

Yes, complete privileges. Unfortunately, LAN has since rigged the accounts so I no longer can test with the local WS account, I have only a domain full admin account - I did test on the server with my separate server local account, still the problem.

This morning I tried (on the NTWS) disconnecting all network maps, running app with every single file involved on C:\. Still the problem, only it manifests differently often. Now, the app often just hangs after a few actions and times out to "Not Responding" (probably at a USE, LOCATE, SEEK, or SELECT SQL, those are the usual code lines where the errors hit). This is meaningful, I'm sure, but just what...??

>>Where is "opportunistic locking"? - I've heard this mentioned before, but cannot locate it on NT.
>
>The first place I look for stuff like this is http://search.microsoft.com/us/dev/ Most times a knowledge base-only search is enough. A quick search for "opportunistic locking" turned up...

Aha, I have MSDN on the NT machine, in fact. I thought it was a simple NT setting - I see it's a deeper subject. I'm reading through these now, thanks.