Sound on engine startup

[_OD_]

BUMP again!
I've recently started playing the game again, there was a STEAM update which fixed the sound, I had gunfire and the engine starting up. This worked for a couple of games and now it has gone again.
At the moment I have no sound for the following:

Engine Startup - sound kicks in when past certain revs

Gunfire - Either mine or enemy

Damage - Either to my aircraft or inflicting it on another aircraft.

There may be more but these are the key ones which are bugging me. Is there any way to resolve this? I am using an onboard Realtek sound card and 5.1 headphones running through the jacks and not USB.

It would be great if there was some kind of reply, even if to say it hasn't been fixed.