Contour II dropping on demand program I'm viewing, and reverting back to last channel watched.

I just had my contour I boxes replaced with the newer contour II and when I watch on demand...The show I'm viewing suddenly drops and it reverts back to last channel watched. The remote is not being touched. This happened 4 times in a 2 hour show. what's up and why is this happening? It's acting like I have hit the LAST button on the remote (but the remote is not being held or moved) I then have to hit the LAST button to take me back to the show I was originally viewing on demand. Had my old contours not been failing I would be begging for them back.