dvr playback issues

For the last few days when I playback recordings, the recordings stop, I get an error message or the three dots, then it starts again, sometimes skipping, sometimes going back and sometimes a shadow appears on the top 1/3 of the screen. Also the menue sometimes lags when I push xfinity button. In general the box has been glitchy. I have restarted several times, did the system refreshed and tightened all the cables. Not sure what the issue might be, but tonight, I could not watch anything because it kept happening. Also happened when I was just watching TV, kept saying channel not available and in general everything was lagging when using the remote. Also changed remote batteries. I decided to watch on my phone through the stream app and it worked fine. Any suggestions? Do I need a new box? And if so, how do I get one? Should I call comcast, is there anything they can do on thier end remotely to fix the issues I am having?