black screen after changing channel restart for fix.. this can't be right?

[Freerider4]

hi all
I am a bit of a newbie , I grabbed the demo a day ago having eyeed up sagetv for a while and done my back ground reading.

Being a canadian user I jumped the hoops to get xml tv working for the listings.I setup the channels thus far I'm impressed. However I now start to run into issues.

I run through my listings I select a channel hit watch now I have no problems I watch I have sound. I decide na I wanna change channel I return to the listings I select a new channel and hit watch now.. bang black screen.

To select the channel a different channel I have to restart Sage.

Why is this. I have hunted high and low.
I know about the FAQ troubleshooting on video issues
I have a hauppage 250PVR running on a soltek nforce 3 mini sytem with 1 gig of ram and a athlon 64 -3200, Nvidia 4200 TI and about 260 gig of HD space - I have the latest drivers from their website. I have the latest directx the latest grahics card drivers the latest java. u name it I done updated.

I have tried changing the video decoder no joy.
I have used the default the sagetv decoder and the Intervideo non ccs codec from hauppage.
I have a main concept one I have used for Vegas, as I edit videos freelance for weddings. I even tried this and bah no joy.

The only thing I have'nt done is stripped Sage and reinstalled it.
BUt then again as a new user I guess you could say I have quite literally done that!
So why do it again? What would it achieve?

What is causing this irritation? suggestions please as this will decide if I buy SageTV or not. I like the idea but this is silly and its buggin the hell out of me.
many thanks in advance