I use modified Ed Rauh API_APIRUN routine from downloads to launch a standalone exe file and wait for completion.

After exe file finished, Alt key stops working in my appl.
For example, Alt+F does not open file menu.

Normal Alt key behaviour is restored if I manually use Alt+Tab to switch to other application and then back to my application.

This is very confusing to users.
Any idea how to fix this ?

Any idea how to fix this?