The maverick wrote:...with no entry showing in recording history.
The recording history only contains
* all the Duplicates that it didn't/won't record (the 28-day rule items)
* all the Conflicts that it couldn't/won't record
* all the items you've explicitly deleted from the ToDo list, and all the 28-day rule Duplicates of those.
For an actual recording [or as with your problem, one that TiVo thinks it's made], it won't appear in the recording history. So in that sense it's not a fully complete "history".
The Virgin TiVo calls the same thing "Recording Hiccups", which I don't like - the 28-day rule is a brilliant feature not a hiccup - but I can see why they don't use the term "recording history" as it implies a complete record.
mrtickle wrote:the STB not delivering a video signal perhaps
It does seem more like the STB being in standby as that's a more likely explanation than the relatively rare hardware glitch.
Instead of waiting for the next failure of something you wanted to watch, why not do a test?
Set up a recording of a 5-minute manual recording on BBC1.
Watch the Tivo change the channel on the STB and start the recording.
As soon as you can, use the Aux bypass button on the tivo remote to check the STB was correctly changed to BBC1 by TiVo.
Then, deliberately put the STB in standby using the STB's own remote, but let TiVo finish the recording for the full 5 minutes.
See how much of a recording your TiVo has, and
let us know how closely the results of this recording match the problem black bar recordings you've had.