Windows 7 - voice/effect sounds low to non existent error

Hi, my explanation will be a bit messy but here goes..

for some reason (this never happened b4 until now ) when i play games, such as Trine 2, dungeon fighter online. All of a sudden the voice noises will be super low or you cant hear anything. Also some games the sound effect will also not be heard. Only the background music. This happens at random times.

As well... When this problem does happen, if i try to play music on windows media player the volume is super low even at sound on 100%.
Also if i play the song on itune, usually everything can be heard but the voice/lyrics.

Im using stereo sound, on earphones,
no enhancements
on 24-bit 48000hz
side, front etc etc is at 100
on latest sound driver according to device update(6.0.1.6251)
motherboard p8z68-v pro