I am attaching one simple vi which demonstrate the problem of user interface hanging.
Perform the following steps
1. Click the stop button twice very quickly so that vi does not get close.
2. Click on the cross icon at the top right corner of the window to close the vi.
3. After that user interface get hangs that is it stop button does not respond to click , you cannot change the scale of gauge or enter text in text box.
Regards
Uttam