I guess this isn't a tivo issue as much as a cable card issue, but ill tell you a interesting problem that I see a connection to.
Tivo is very solid (except for the very little 1 second audio drops that I hear everyonce in a bluemoon). I barely watch on demand at all, but lately I've watched 2 on demand movies on my Scientific Atlanta 8300hd box in my bedroom at night.
I noticed that everytime I watched a on demand from the previous night, my cable cards lose the premium channels on my Tivo, when i check it in the morning. Theres a simple way to fix this (just restart the tivo).
Has anyone else had this problem or something similiar?