Did you install the
drivers for the TV Tuner card? If so, go into safe mode and remove them - Windows 7 has native
drivers that work perfectly fine.
Same holds true for the WinTV app - that needs to be installed in Vista compatibility mode (and even then it pretty much sucks in Win 7).
And if you want answers faster, please use a more descriptive title - just saying TV Tuner is not helpful to anyone at all, neither folks answering posts, not *future* readers looking for an answer to a problem....