DVR replay stutter/freeze/record over top of other shows

I have a Cox DVR set top box hooked to a Panasonic flat screen.

The DVR has the "rovi" software.  The TV  has no problems and it gets an excellent picture and sound through the box.  It is at replay of recorded shows that I have problems.  The picture and sound will stop and go, not always together.  There are times that I can see another show recorded and mixed into the one I want to watch.  The problem is much worse the longer the time between recording and watching.  The picutre will sometimes break into pixels.  I have unplugged and replugged the DVR to force a reboot which will help briefly, but not cure.

Has anyone else experienced this or similar problems?