TV tuner problems Ati 550

I went from a ati aiw 9600xt to a Shappire Threatix 550. The 550 didnt work with windows media center untill I baught a new Gigabyte 5200 128meg video card. Now everything seemed fine. I am using power cinema that cames with the card, the tv isnt very smooth. The image freezes or the audio stops when I do other stuff. This never happened with ati aiw 9600. When using windows 2005 media center, the tv works fine, excepted, I get small lines in the image almost like shadows.
Thanks

check all your cables, make sure all the drivers are installed, not just the Power Cinema.