You can download a little test here:

http://www.infinite-dreams.de/3dgs/media_play-issue.zip

I could reproduce the problem after 6 tries using the current beta (but I had the same problem with former GS releases).

The acklog.txt in the zip-file is the one when I produced the problem.

I added a beep() and a logmessage after the code that should wait for media_playing(). So if you hear the beep right after starting the "game" you produced the problem.

I hope this helps.

Regards,
Pegamode.