Last night, I had one of the weirdest problems I've ever seen on a Tivo.
I was browsing the listings, and set recordings for two episodes of the 2013 World Series of Poker. For some reason, I had thought maybe I missed those episodes and/or they were two full hour long episodes of what previously was shown as a 1.5 hour episode(*).
It was 8:00 or 8:01 (the first episode had just barely started).
I realized I had already recorded those episodes... But the previously recorded episodes WERE NO LONGER IN MY Now Playing list. I even have a screenshot of my kmttg session from VERY soon before (within an hour, I think much sooner), that shows those two episodes still there. They were NOT in recently deleted, and trying to actually transfer them with kmttg failed.
The Tivo WASN'T completely full, and there were a bunch of other recordings in recently deleted.
I don't completely discount the infinitesimal possibility of me accidentally deleting them, but it seems very unlikely.
I recorded them last night, and set recordings again tonight (to get the min or so I missed at the beginning).. and they're on On Demand.. so I am in no danger of actually missing them..
But I have never noticed recordings *seemingly* mysteriously being deleted.
(*) I asked in the SP alerts thread, but have since found out that the On Demand listings _do_ show two "hour" (~47 min) episodes even for the 1.5 hour episodes sporadically for the past few weeks.