This is an odd thing that has never happened to me before.
I'm using a 17' Viewsonic graphic series. Monitor is probably around 3-4 years old. I have only tried with one other game so far and I don't get the same result.
In AH, when I am in the game, I get this high-pitched squealing noise. It's coming from my monitor. (I can turn it off and it goes away) and it only happens in the game. Once I leave the game it goes away.
I tried Call of Duty and it didn't do it in there.
Using the same resolution in both games 1024*768
Any ideas?