Just upgraded cable box yesterday to an X1 and now picture and sound stutters, pauses and is very choppy. Sound is not in sync. I have restarted the box and still no success.
Unscrew/screw back on EVERY coax connection you can find, all the way from where the coax enters your residence to the wall plate to the TV/
Most likely you have a signal issue. You could use a tech to troubleshoot. You will want all connectors including behind wall plates inspected and ideally replaced. The line from the pole to the house will need to be inspected. It could be water damaged (common if old). The box itself is almost never the cause of your symptoms.