Internal Audio Problem Options

[zenke]

I am experiencing a strange issue with internal/external audio
I am on OSX 10.3.9
I have an edirol FA 101 Firewire audio interface. It has always worked well.
I rarely use internal audio
Recently when playing a youtube video the audio was internal coming out of the internal speakers.
This is also the case if using real player eg for playing a radio programme.
however if I open audio software eg Ableton line the edirol is used.
the other strange thing is that if I try to mute internal audio using f keys nothing happens.
I can't get the edirol to be recognised by real player, windoes player etc. It is set up in audio preferences though.
anyone else had this happen and does anyone have any suggestions.
It used to work fine

thanks
z