Here are some basic setup info that I do know
Tuner Card - Hauppauge PVR-150
OS - Windows XP SP2
PC - Athlon XP 2000
RAM - 512 MB
MP - latest download 0.2
DirecTV Satellite External Box
Hauppauge IRBlaster
Zap2it Plugin
When I go to MyTV, I can view channel 3 which is the Internal TV channel the settop box send out to the PVR-150 card. Although when I tune into another channel, the screen goes black ( and no sound) on my PC but have another TV hooked up to the DirecTv box and the channel will change on it. So I know that the IRBlaster is working with MP for changing channels. It almost seems that MP is changing "external set top box" like it was a "TV tuner card".
I hope this made sense.
Thanks!