Windows 7: Sound problems while gaming (SBK2011)

Hi,
I was thinking weather to open this thread in "Gaming", but then i decided not to because the problem is with the sound...

When the game is launched (SBK2011 stands for World Superbike 2011- it's a racing game), every thing is normal (the loading music)... just till i should enter the track. the the sound of MY bike is not heard and that is how it stays to the end of the race. I made a video gameplay with Dxtory in order to show you what the problem looks like, but when I played the video in Media player- every thing seems normal (all sounds are clearly heard) !?!?!? I have Realtek High definition audio drivers, and thats not the problem. I noticed this a few days ago and since then I'm trying to solve this....
Any kind of help is appreciated