I was playing Halo in DD yesterday in all it's engulfing sound fx glory. Today I tried to play it, the DD light comes on and sound is coming out, out of every speaker except the center channel. I jiggled the optical cable (using HD pack) and nothing happened. I unplug and re-plug in both sides and still nothing. I ejected Halo and popped in Gladiator. The DD soundtrack works perfectly with sound coming through the center speaker. I turn off my receiver and turn off the Xbox. I try playing Halo again and still, nothing is coming out of the center channel, but the other channels work perfectly. The DD is still on, and all the speakers are indicated as working. I go into the Xbox's system settings and make sure DD and DTS are enabled, which they are. Anyone else have this problem? Hopefully not, it totally sucks, I won't play Halo again until I can get this fixed. Some of you might think this is dumb since I can just switch it to stereo, but I'm sure some will agree; if I buy a game that says Dolby Digital 5.1 sound, and I spent a good amount of money on a DD receiver with 6 speakers, then I want to play it in DD 5.1. I don't want to go through the rest of this game playing it crippled. So do you think it's the Xbox sound processor which is screwing up? What should I do, exchange my copy of Halo for another, exchange the HD pack, or exchange the Xbox? I could also call tech support or maybe even wait it out a few days and see if it starts working again. bleh.... $300 and something so minor can really make you feel like never wanting to buy anthoer Microsoft product again. Which is sad because I really love this game.