I've had my TIVO box for years, these days it's pretty much useless. If I pause live tv, then when I restart it, it stutters and stops and starts. The program is completely unwatchable. Watching any of the catch up services is the same. I've had enough and I'm seriously thinking about cancelling my subscription.
I tend to just watch everything via online services on my iPad these days as it's reliable!
Thanks for posting and I'm sorry to learn you're experiencing problems with the On Demand.
I'd like to arrange for one of our engineers to check your TiVo® box so I'm just going to pop you a private message with appointment times which you can find if you click on the purple envelope at the top right of the screen.