I found out something strange. After a bit of testing, I think the high pitched nosie only happens when my resolution is 1024x768 (changed it in the game's options, not in Windows). When I change it to 800x600 it seems fine. 800x600 is my monitor's native resolution. It is an old 15" CRT monitor (13.9" viewable). I just don't know why it only happens in DW.