Hi Mark Blue!
Never read a post with such a consciousness on how and why BSplayer started to have problems :shock: :)
Unfortunally I don't have XviD files with AC3 audio.. but it seems to me you answered all the questions by yourself (at least you auto-suggested few hints :lol: )
You can try to roll back to your previous skin, to uninstall your recently installed AC3 Decompressor, to raise BSplayer/Filter priority..
I saw you on the forum quite often in last two days, and now I know why (well, I think this was the reason :roll: ) :)
Try all this things (maybe it's better one by one) and let us know how your PC behave