Really weird audio problem

So I was playing on Close Cliffs and got to wave 80.. I then started to lag a little towards the end of the game so decided to lower graphics. I thought the game was really ugly and changed the graphics back. I finish game and later go into another and now I have an audio issue.
 
No music plays ever, during the menu screen or during games. I occassionaly here the character and orcs talk but its intermittent compared to what it used to be, and items sounds are intermittent also, for example charging the sorceress staff will make the charge sound 50% of the time and 50% of the time it wont -_-. 
I also hear combo streaks sound occasionally even though I can see combos being made but sometimes the sound hits and sometimes not.
 
No other game has an issue, drivers are all up to date and everything else is fine and dandy. I bring up about changing graphics because the audio started playing up less then 20 minutes after doing this change which is the only thing I can think of that I have changed in omd2 aswell as changing the resolution back.
 
Help appreciated =)