League of Legends in-game (no client sounds) Any other game Browser WMP
It's the second time this has happened, always caused by Mass Effect (series), I thought. Whenever I opened any of ME games, they will have no cut scene sound, except for dialogue lines within the cut scene. Afterwards, ME would proceed to being the only application in my computer with working sound, until League of Legends (in game). I fixed it the 1rst time, by scanning my computer and finding a trojan in my Creative drivers .dlls, cleaned it, reinstalled drivers, sucess.
I played ME3, gave me no problems, went back to 1, all my PC goes silent again, and I have no trojan .dll any more, and proceeded to reinstalling the drivers regardless. Windows test sounds work, some Football Manager 2012 sounds, LoL in-game, and the green sound bar moves.
If on Windows 7 have you installed the ALchemy drivers also? They are needed if you are running sound to emulate surround sound on creative cards.
Also try uninstalling the drivers and letting Windows install the default Microsoft ones, as a last resort.
Difficult to diagnose due to the fact it could be a lot of factors causing this, even programs that knock out the focus on game windows so sound disappears.
Ah, sorry forgot this thread.
I had the green cord from my 5.1 speakers plugged into the very greenish grey slot in my soundcard. That was causing all problems, now I get sound in all my games, and Mass Effect doesn't take all sound from my computer anymore.