Firstly I'd like to welcome you to the forums and say that I'm really sorry to hear that you've been experiencing freezing on playback, I really do appreciate how frustrating this is, as I had a similar issue myself a few years ago.
I've done some checks on your TiVo® and can see an error on the hard drive of the TiVo® so I'd like to arrange for someone to call out and take a closer look at things.
I'll send you a private message in order to get things moving with this, please look to the top right of this page where you'll see a purple envelope icon, click on this and you'll see my message.
Many thanks and apologies once more.
P.S. It's very likely that the engineer will swap the TiVo® for a different one, whilst we are unable to save any of the recordings, there are things like series links, wish lists etc that we are able to back up. Why not check out http://virg.co/boxswap to learn how to back up some of the settings you already have.