DVR recording multiple hours longer than it should

Our DVR seems to have a mind of it's own. If we set it to record a regularly scheduled show, it either records as expected, or it may record for many hours longer than the program. It may start recording hours before the show comes on and stop recording hours afterwards. Or it may start on time but not stop recording at all. Also, if we press the record button during a program, it will start recording from the time the channel was last changed, meaning it will record the previous 3 1/2 hours of programming if that's when the channel was last changed.  Also, it doesn't only record until the end of the current show.  It will record until it decides to stop.

This has become a very frustrating issue.  Any ideas are welcome.

I saw a similar post, but that fix action did not work.

Thanks.