>I can't consistently reproduce why I get "access denied", but I do get it from time to time.

My guess is that it ain't the provider per se. "Access denied" tells me it's a perms issue, or contention issue. Threading issues generally manifest themselves with different errors, such as server 500 (the process hosting vfpoledb.dll crashed because it was trying to access something it shouldn't, like a connection handle). I'll try to fiddle with this tomorrow to see if I can repro.