all my TiVo boxes are becoming unwatchable. I had an engineer here a couple of weeks ago to look at my broadband which was apparently fine but he did notice the TV signal was poor with one or two channels breaking up. He called another engineer to look at it but I heard nothing more. Now many channels such as ITV2 are unwatchable, breaking up and stalling.
First of all check all your connections. The co-ax cable should be firmly seated (not overtight). Leads to the tv should also be secure. Next thing to try is a box reboot (power off via the rocker switch on the rear of the tivo). If the problem persists call the faultline they can check the signals remotely and advise you further.