Generally with media center and cablecard tuners you don't want any extra codecs/filters/splitters etc. If you must have them for something else, I would research the ones you are getting that there are no problems with them... right now the only pack I trust is shark007 as if I break something, an uninstall/reinstall of it seems to fix it... others seem to always make some change someplace that doesn't uninstall well.
Usually this problem is actually caused when going through an AVR and disabling the "navigation" sounds in the guide fixes it. It has something to do with having to switch between stereo/pcm and 5.1 channel (dolby) sound. My understanding some AVRs and/or sound cards are better than others at handling this than others and I believe some have suggested firmware upgrades to the AVR in the past.
My hearing has gotten so bad over the years, that captions are a must and for me to listen I use a bluetooth headset and stereo is all I need as often the rear channels overwhelm what I can hear from the front.