I ran into a VERY frustrating problem. I noticed that the sound from my rear speakers was coming out of the front speakers, and the sub wasn’t working at all. After checking all my wiring about 5 times, going over every speaker setting over and over, removing the Sound Card and all drivers and re-installing it, I eventually rebuilt my PC. To my delight, 5.1 sound was working again. I wasn’t really happy though since I didn’t know what had caused it, and rebuilding is a real pain. Then, suddenly, it was broken again. I realised the only thing I had changed was to install my Logitech WebCam Fusion, and the latest drivers. This WebCam includes a mic and during config changes some sound settings. I disabled the mic device in Windows device manager, and suddenly 5.1 was working. Enable, and it breaks. I then found this thread in the Creative Web Site, which was dissapointing since it seemed other people have the same issue, but there is no fix as yet, besides disabling the mic, which sucks, because the mic is cool.
Besides this little (actually big) glitch, the WebCam Fusion is a great little camera, and it works very well with Skype 2.0 and MSN Messenger.
I installed the latest Creative Audigy 2 Drivers (dated Jan 2006) and with eager anticipation, enabled the Fusion mic. Alas, no surround speakers! I then logged a call with Logitech who suggested I try disabling AEC. I did try this before, but I did it again, and now everything is working!!! Must be the new drivers and this AEC thing.