Exactly got the same problem, and its strange, cause I use mala (1.74) on 3 different pcs (2 with windows 7, and a netbook with windows XP), but is the netbook one that gives me this problem.
The problem is just as described, if Fadein/out background music on mala is ON, during game menu all goes well, but when i start a game, mala fades music to off (windows wave on mixer stays on 0 level)..and then the game that has been recetly loaded, plays with no sound (entire windows has no sound). When you come to mala menu, fade goes up, and entire Windows has sound another time.
If i uncheck fade in/out on mala, all goes well, music on mala background, and game music works...but well, background music stops with no fade after loading a game, giving an "un-stetic" effect.