Nvidia 6800 GT (code 12) error when new TV tuner card installed

[Mordoc]

I bought a Conexant TV tuner card, the video magician package. I have a home built system: Windows XP, Abit IC7-G motherboard, and an Nvidia GeForce 6800 GT video card. Everything has worked great with the system until i put the tv tuner into the system. Now, my video looks all screwy. My video card gets a (code 12) error with the tv tuner in the motherboard. I've tried switching pci slots but it hasn't helped. I've also tried moving around my sound card and Network card but that hasn't seemed to make a difference either. The computer works fine again once i take out the tv/av/dv decoder. If anyone has any ideas that might help me it would be much appreciated!