Tonight my Tivo had some kind of freak out when I switched it on, and rebooted several times without ever starting fully. It was also making a loud clicking noise - not the usual soft tick, this was the sort of noise that I associate with failing computer hard drives.
Eventually I turned it off & back on with the rocker switch on the back. It booted up OK, but the loud clicking continued & the menus were very unresponsive.
When I finally got into My Recordings, I could see it was 96% full. I wondered if this was causing the Tivo problems so I deleted some old junk & got it down to about 85%. It carried on clicking, getting slightly worse when I tried to play back a recorded show, but is currently quiet.
I know this sort of thing doesn't bode well. I've looked in the diagnostic menu but can't find anything that shows the health of the HDD. Is this something you can check from your end?