Unable to watch DVR'd shows; play freezes, audio bleeds in

Over the past week, I've had lots of issues with my DVR.  Have had this DVR for over 2 years and never had a problem with it before.  Shows that aren't in my series list are recording - just random things.  Shows that ARE in my list are NOT recording.  During playback, the show will usually "freeze" at some point and then not progress forward, meaning I cannot view the entire episode.  Exiting and attempting to resume results in a black screen and no progression of playback.  Fast forward fails to move through the "problem area"; it just stops moving the progression bar.  Audio from somewhere else (unsure where this is coming from; today it sounds like a basketball game in my episode of Big Bang Theory) will also bleed in during playback and then the picture freezes.  For more episodes than not, I'm unable to view anything in its entirety.  Have done more than one reset, thinking this would solve the problem.  Weather doesn't seem to be a factor, either.  Any suggestions would be welcome.