DVR Cutting Off Shows 5 to 10 Minutes Early (Before programmed end)

Recent recordings on my Cox DVR are cutting out five to ten minutes before the end of the show (both the actual end and the end of the record time).   In other words, the recording should be for one hour and are actually only about 50 minutes or so. 

I have reset the box and checked the record times, and they seem correct.  It seems like for most shows recorded over the last month or so (it doesn't seem to happen on older material recorded months ago), my wife and I watch up until the last ten minutes or so, the "Delete Now/Delete Later" dialogue comes up, and we're out of luck.  If the show is On Demand, we can watch, but with no "Fast Forward" we have to either watch through or jump through to get to the end.

FYI, we are at about 45% to 48% full, and about 100 shows, more or less.

Very unpleasant viewing experience.