I just went through all my instructions on a fresh flash of OS2008 (50-2). The one thing I can think of is that you definitely need to reboot. Also if you have the charger plugged in when you attempt to "Switch off!" it won't actually switch all the way off. Unplug the charger, switch off, turn back on, plug charger in and see if that works. I really don't have any more ideas about this, but maybe if you could show me the output mplayer gives, I might be able to help.

-John