I noticed a weird audio bug - often after jumping into the water I would hear an annoying buzzing / whiffing noise repeatedly a couple of times a second. I would only hear it when above the water level and it would never go away until I opened a door and left to a new interior/exterior area.

I tracked it down to using Creative ALchemy - a program that installs a dsound.dll in the game's folder and enables support for DirectMusic / DirectSound environmental audio that were disabled in Vista. (I think you need Creative Audio Hardware to use this program though there might be freeware alternatives if you don't have such hardware?).

Anyway, I think I may have fixed my problem by running Creative ALchemy and editing the game's profile to use 50 ms Duration instead of 25 ms Duration. I can't guarantee it will fix it though, since the problem was kind of sporadic to begin with. If you have this problem, good luck and please let others know if you found a solution.
FYI you can find some details on Creative ALchemy settings here http://connect.creativelabs.com/alchemy/Downloads/ALchemy%20Quick%20Start.pdf