DVR - 2 hour recording stops 20 min before end

I've got an odd problem.  Some DVR recorded programs exit out when watching them at about the 20 min left in the program mark.  So far I have only had this happen on programs that are 2 hours long, and programs that are on ABC.  This has happened multiple times on The Bachelorette and 20/20.  I have not noticed this happening on other 2 hour programs on other stations.