I see from the timestamps the problem popped up today. I had the same problem this morning and figured that maybe an update during the night went wrong.
Make sure all boxes in the house are on before you start this. Press the xfinity menu button. Toggle to the Gear icon/Settings. Go to Help. Your first line will be Troubleshooting. Toggle over to System Refresh. Press OK and wait (may be up to 20 minutes). Mine was restored to normal functioning with the rewind, <<, >||, and >> working when my screen came back up.
... View more