Cannot switch from one tuner to another

[revrenhex]

I have a Hauppauge MCE150 & a HVR1600. Ive got it set up with both and doing clearqam. I can start the tv, and watch either qam or regular tv with no problems. the problem is if I try to switch from one to the other, i just get a black screen with no audio. I have to either get out of pvrx2 Or load a movie/recorded show, let it start then go back to TV to get back to watchable TV. As long as a I stay with whichever tv format I started with Its ok, just between the two is a problem.

Thinking it was a codec issue, ive switched everything in the system into every combo I can, with no help.

Any ideas?