Fast forwarding randomly causes recording to go back to beginning

This seems to happen only when recording a live sports program (i.e. long) and then viewing the program from the VCR while it is still recording.  Sometimes when I hit fast forward the recording just goes back to the beginning and loses my place.  Other times it fast forwards fine but when I stop fast forwarding it goes back to the beginning, and still other times it shows that it went back to the beginning but it actually doesn't.  I don't think this happens if I wait to view the program until the recording is finished but for football games or golf tournaments this is very frustrating.