On November 1, 2013, I contacted CBSAtlanta to ask whether they were aware of the stutter - video appears to be a s-l-o-w strobe effect with accompanying audio, so it's not a problem with one or the other. It had been noticeable at 11PM when the CBSNews started, although now we see it every hour. I switch to news on another channel.
CBS' reply: "Thank you for your email. I know some viewers have been experiencing issues through Comcast, and I believe it was a technical issue they are trying to get resolved. Since I am unsure if it is the same issue, I am forwarding your email to my Chief Engineer."
My idea is that this is caused by a signal being sent from CBS or, more likely, Comcast on the hour, since I was watching the Vanderbilt-Kentucky football game (November 16) on channel 7 / WPCH, and when the picture stuttered, we looked at the time - 1:00PM. It affects the start of our favorite programs, especially on CBS.
When I checked with my daughter who also has Comcast but pays for HD programming, they don't see it on 809 / HD. Evidently it occurs only on standard broadcast.
Is this an effort by Comcast to get us to pay for HD every month?
CBS was again (January 13, 2014) contacted, and they replied "have reached out to comcast"