>>>I'm testing a long running vfp program and found these problems
>>>
>>>Wait window messages freeze (in different parts during different runs)
>>>Added debugout message, but it also freezes.
>>>I set escape on, but program doesn't respond to ESC
>>>Added saving message to disk which shows that program continues to run
>>>Finally process finishes correctly
>>>
>>>It's almost like it locks screen and keyboard out.
>>>
>>>I have windows 7 64 bit and VFP sp2. Any idea what may be the problem?
>>
>>Naoto and Rick have pointed out the most likely thing, that you need to periodically issue DOEVENTS during your heavy processing.
>>
>>I agree with Dragan's idea of using something other than WAIT as a progress display. For my long-running/unattended processes I do a lot of logging to text files, and I echo some of the log entries (including datetime) to the bottom of a scrolling editbox on a form.
>>
>>WAIT is something of an odd duck, present in the product since the DOS days. I don't know how it's been implemented in Win32 but I suspect it's a kludge. I avoid it if at all possible; if I need to use it I make sure to issue WAIT CLEAR when I'm done with it (or before issuing another WAIT).
>>
>>Long-running SQL queries block and can make the system unresponsive. Many years ago I was running large queries on slow hardware so I experimented with something like this:
>>

>>SELECT ;
>>  ColumnsYouWant ;
>>  , MyUDF( DATETIME( ) ) AS JunkColumn ;
>>  FROM ...
>>
>>FUNCTION MyUDF
>>LPARAMETERS ttDT
>>
>>* Run every 5 seconds, (pseudocode only, below won't work as-is):
>>IF MOD( SEC( ttDT ), 5 ) = 0
>>  DOEVENTS
>>
>>ENDIF
>>
>>RETURN Something
>>

>>Finally, there is the question of I/O to your disk/virtual memory subsystem. If your processing hammers the disk then your system as a whole (including UI) will be unresponsive, that's one of the weaknesses of current versions of Windows.
>
>Thank you Al and all for the insight and ideas.
>
>Issuing DOEVENTS periodically is not a complete solution, but it helps.
>
>Setting _VFP.autoyield = .T. seems to solve the problem but creates a risk if user clicks on an ActiveX object. Is this the only disadvantage of setting _VFP.autoyield = .T.? If there are no Activex controls alive is there another reason not to set _VFP.Autoyield = .F.?
>
>Thanks,
>
>Alex

I have always used autoyield = .T. which is default, and I have never had any problems with that.