You likely have signal issues related to the coax wiring somewhere. Call and schedule a tech visit.
Agree with Reds,
You will need to set up a service call. When you do that, avoid resetting any equipment for at least six hours (boxes, modems, routers) so the tech can take a signal test. Reboots of equipment will set the error codes back to zero and you don't want that.
Than, when the tech comes, tune to the channels that are breaking up, so that he take a signal reading. You may have cable line issues. A new box will never resolve signal or line issues,
First thing in this type of scenario is to check the coaxial cable. Is it snug on the back of the cable box and at the wall outlet? Are you using a splitter? If so how does it look? Corroded or any apparent damage/wear? Do you see any kinks or damage on the coaxial anywhere?
If everything checks out well and you are still having problems I would definitely suggest a tech visit.
You can also contact our Social Media Care team at:
Spectrum-Social Media Customer Care
Lead Moderator-Community Forums
Another possibility is that your area was switched to fully encrypted video overnight and your set-top box didn't get the update programming for some reason. If you include your ZIP Code we can check n that for you. Spectrum mailed out cutover notices but folks who tell their bank to auto-pay the cable bill monthly might not have seen the instructions.