Contour Record 6 DVR records but playback starts at the end of recording.

I have a Contour Record 6 DVR , ARRIS Model AX013ANM, that I have NASCAR races scheduled to record just about everything NASCAR. It records races usually on Friday, Saturday & the main CUP race on Sunday. The Friday & Saturday races record & PLAY fine. The last 3 Sunday races record I have recorded, when I playback the recordings it says they have recorded & at the correct time but when I attempt to playback, the recording starts at the end of the race! I have researched & confirmed the races started on time, but all I get is the very end of the race!  Even though the recording says there is 4 hours of recording.