Not sure where you are located but it could be the signal your local CBS affiliate is sending. Since the bandwith
is higher on verizon vs comcast there should be an improvement and not a degredation. If you notice the problem on multiple channels and not just CBS I'd have them look at the STB and cabling if it is not something as simple as a setting change that needs to be made.
I remember having the same issue with cbs last fall watching NCIS,but i use a tivo premiere. I never did find ou what the problem was,makes me the problem is directly from CBS, BTW i live in apple valley california and our local CBS station is from los angeles,if i have problems again this year i'll be contacting CBS to try and resolve yhis problem!,on my tv NCIS looked like i was watching tv through a screen door! I think the real culpirt are the samsung tvs as thats what i have a samsung 55"" 6000.