I haven't tried MOG for a couple weeks. I logged on today, and a pop-up message appeared. It said:
"Flash version 11.3, the version you have installed, has acknowledged problems with audio playback. MOG recommends downgrading Flash to a previous version until Adobe has released an update which fixes these bugs."
Perhaps the mystery of why some people have been having problems with MOG and others haven't is solved! MOG says I need to downgrade my version of Flash for it to work correctly! This is on my Windows Vista PC.