I ran across this thread and changed the configuration settings that jumperman posted. This may help some of you that I've seen experiencing the same problem
http://iptvtalk.net/showthread.php?23249-A-lot-channels-are-black-screen&referrerid=46003
http://iptvtalk.net/showthread.php?23249-A-lot-channels-are-black-screen&referrerid=46003