Hi here are my pc specs

ASUS M4N98TD EVO
AMD PhenomII 1100T x6 3.3 GHz
Nvidia Gainward 460 GS
Creative Titanium HD
Croshair 950watt psu
Windows 7 pro 64bit

Now for the problem .When I start the game I'm Able to hear music .As soon as I get into game play A NPC starts talking .I am unable to hear what the NPC is saying and the music is still playing .Also Since I have got it from steam I have validated my files and always get 1 file fails to validate .When I load the game up after validation I get FNV Has stopped working .Any Help will be Appreciated