Assuming that Amazing Charts was properly logged of you can also get this message by 'over double clicking'. Some people (myself included) click too much too quick. You end up double clicking twice and it will try to open program twice.
You can adjust double click speed in control panel. But a sure fire way to avoid this is to just click once to select icon & then press the Enter key.
It seems to me that the programmers could instead of sending the 'AC is already running' message tell you an AC process is running and ask if you wanted to shut it down then load AC.
