>>The temp files that VFP creates are being scanned and have a significant effect on performance.

IME temp files *must* go in a different location from %TEMP%, because %TEMP% is where payloads often turn up and many customers insist on scanning it. Then your app's temp file folder needs to be excluded from scanning without fail. It's no longer enough to exclude dbf/cdx etc as used to be recommended: under load or on a modern server, a virus scanner can cause unrecognizable access errors to files that don't match the dbf() of the cursor you're trying to access. There's some sort of fleeting VFP internal file that contributes to an intermittent error like this- I think because the error only manifests if the cursor spools to disk. You could try messing with MEMLIMIT to see if that changes the frequency (of cursors spooling to disk) though VFP seems to dance to its own tune regardless.