well, well, just in case someone else is trying to deal with this:
The new nvidia drivers (since version ???.5336) are not compatible with the rivaTV module (wich I was trying to use to access the video input) and probably with most other available modules that do the same.
Users that upgraded form a compatible version to the new nvidia driver, suddenly could no longer use tv or video input and promptly posted their complaints on the nvidia forum, check it out at:
the most important part: "The NVIDIA driver claims resources using Linux mechanisms designed, in part, to prevent multiple drivers from driving the same resource. Though earlier driver releases didn't do this to the same extent, future releases will continue to do so. If you wish to use rivatv, I guess you'll need to hack either driver (nvidia, rivatv - at your own risk) or use the XFree86 nv driver, instead."
we can only hope the developers on the rivatv project can work around this problem and find a solution, here is a link to their forums:
the relevant thread on this matter: