Hi Dean. Thanks for the ideas. The VI was not re-entrant (since it is called in only one place, and has only one data set), but I tried making it plus its subvis re-entrant, as you suggested. No difference.
FYI, I have observed that the problem only occurs within the VIs memory space - e.g. if I am running this VI uncompiled under LV, clicking on the title bar of any uncompiled VI currently open (whether running or not) causes every running VI to stop for about 250 msec. However, if I have another App running - e.g. a compiled LV App (which Windows would assign to a separate memory space), it does not stop. Similarly, if I click on this compiled VI (exe), it stops for 250 msec, but has no effect on the uncompiled VIs. I will try splitting the VIs when I get some time, and will report back.
