>>>>I don't think DoEvents and AutoYield are relevant for DLL.
>>>
>>>Communications via COM depend on parts of Windows that are outside of VFP. If VFP is blocking processing of Windows events, it might interfere with that.
>>>
>>>Testing of these is easy, literally one line of code each.
>>
>>Seems like it made no difference. I added DOEVENTS following with
>>_VFP.AutoYield = .f.
>>
>>---------------------------
>>I'm closing for now, will resume Saturday night.
>
>_VFP.AutoYield is global, set it once before any of your test code runs.
>
>I'd put DOEVENTS as the last line in your loop.
>
>To be thorough, you have 4 tests:
>
>1. .AutoYield = .T., no DOEVENTS
>2. .AutoYield = .T., with DOEVENTS
>3. .AutoYield = .F., no DOEVENTS
>4. .AutoYield = .F., with DOEVENTS

I see, you suggest to put it in the test procedure, not in the dll's code?