I have had the status bar stick multiple times and do other strange things - once I had it stick on the same show for over 18 hours. Was not on a HR24 though, but a HR20 iirc.
I had a HR20 that was once reporting 963 hours in the time bar.
The time bar is based on the Presentation Time Stamp which lives in packet headers, and is analogous to timecode in analog video. But there is really no redundancy or forward error correction for that, other than it repeats in, IIRC, every 10 packets or so. So if it gets corrupted enough (enough of them damaged in a row) the DVR can get confused about just where it is in the world, often defaultiing to 00:00:00. Sometimes you can fast-forward past one of those blips; other times you can't. If the PST is good again 30 seconds down the recording, you might be able to "jump" over it, as the jump feature looks for a PST that is 30 seconds (nearest I-frame to 30, actually) greater than the present PST, and sends the playback there non-linearly like on a DVD, which is how the jump can be instantaneous.
So what is important here is that the video has redundancy in FEC, but the PST does not, which means that if your signal is marginal, there may be corrupted video packets that get fixed by FEC, while PST does not have that option. That means that the video may look fine, but the PST might be corrupted enough to cause this issue, on rare occasion. It does seem unusual that it might be tied to a up rev, though, so maybe something else is causing this for a different reason other than marginal reception. But it would not hurt to verify that.