sound missing whilst flying

[mtvexl23]

I've just fired up BoB again after a long time away and it worked fine but now after I leave it for a while (still loaded) and go back and go to fly again and it has gone through the process of loading the weather etc, there is no sound whilst flying. I quit the flying and go back to see what's going on in the options and I'm getting the music and the sounds of changing options, so the sound is working I uninstalled it and re-installed but the same thing happens. The sound sort of crashes when you enter the flight but not during options. Once it has happened the sound doesn't come back whilst flying not even when you quit and reload.
Any ideas.

[Boreas]

So far the only thing I can think of is changing the sound driver mode in the game menu. I have it on primary sound driver, there might also be default and speakers.