I have rebooted my Tivo many times, and earlier it wasn't getting anywhere (blue lights of death?), but today it has reached "Preparing channel information" and has been stuck at 25% all day.
No matter how many times I reboot it, it will get back to that screen eventually and be stuck at 25%.
If you leave it long enough it times out and goes to the home screen or it goes to an error message that says it was unable to prepare channel information. On the home menu you can't do anything - I tried to navigate to the settings menu and it just shows a blank screen.