I have a VFP6 app that has a modal form that calls other modal form that may call another modal form. These forms have been behaving well for years so that when exiting a nested modal form the focus reverts back to the calling form as it should.

Recently on one user's computer with Win XP, it occasionally will return focus to one of the earlier modal forms leaving the one that should have focus behind another form and the app hangs with no way to return focus to the correct form.

How can I detect and prevent this to be sure that the correct form gets focus on exiting the called modal form?