>>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