all relevant info here;

http://forum.team-mediaportal.com/developers-lounge-70/channels-same-mux-not-released-properly-45695/

in short;
when concurrent channels are being decodec with a CAM the channels that are eventually stopped do not really stop/dispose properly until the last channel on the same mux is stopped also.

this leads to a CAM limit that cant be trusted along with waste of resources (CAM decoding irrelevant channels etc.)