Install matroska, lose audio

[artki]

using version .86, build 499.

I downloaded the latest Matroska Playback pack (to let BSPlayer handle MKV files.). Installed it. The files played fine, audio was a touch low.
Poked around various BSPlayer menus found something that dealt with AC3 that had a volume level control set to the middle. I raised it to the max, volume was the way I liked it.
Looked at more menus, checked out the new options. Suddenly, I had no audio. Even worse, the menus that I was looking at were no longer part of BSPlayer! Under PROPERTIES where I had been seeing 5-7 choices now there was only DIVX DECODER FILTER. That AC3 thing had been there before. I still had audio in other media players.
Uninstalled Matroska, Unistalled BSPlayer.
Reinstall BSPlayer. Everthing works. There are now 3 choices under PROPERTIES - DEFAULT DIRECT SOUND DEVICE, MPEG LAYER-3 DECODER and that divx decoder filter.
Installed Matroska. No audio. down to 1 choice under properties. (the divx thing). Unistalled Matroska. Audio returns.

Whew. What's going on here?!