Sound/music stops working after intro videos

[schnappkatze]

I have weird sound issue: I works when I start the game until I get into the start menu, then stops completely, even if I then get into a game. The game just has no sound.

Specifically, it works for the intro videos and for the "Press button to start" - screen, even if I let that running for a minute or two. Only when I press a button to enter the menu, the sound and music stops working, even when I start a campaign and watch the intro video.

When I click "Quit to desktop" and confirm, the sound/music suddenly starts working again for a few seconds until the game manages to close itself.

Anybody ever had that problem? What can I do? It worked well for 20 hours, until I recently reinstalled it. The only difference is that I now only have Halo 2 installed (playing through them in chronological order).