Yeah its a known problem for some people. But the more common problem is that the sound is very sqeeky and speeded up which is the problem i had. So im not sure if this will work for u but its a worth a go. here is the fix......
(vista)
Go to your control pannel,
Go onto sound
On the playback tab select your device that your currently using.
Then click on that device and select Propertise
Select the advanced tab
In the defult format area select.... "2 channel 24 bit 44100HZ studio quality". Or one at a lower value.
Fixed it for me but good luck.
i have 5.1 speakers