Perhaps a Moderator can confirm this behavior. Occasionally, while I'm watching Cox TV, a similar screen will replace my program. It's just like Elizabeth described: a yellow box with "Get this Program Now" and a phone number to order the channel. It displays for about 5 seconds then returns to my program. It's frustrating because I already subscribe to the channel, but it has always cleared.
In a long-ago post, either a Cox moderator or a knowledgeable contributor explained the screen. The screen will appear while the Cox box is synching with the local distribution facility. When live TV stops while synching, the Cox box can only respond with this screen...because it has to display something.
Therefore, if Elizabeth is constantly receiving this screen, her box isn't synching with the local distribution facility, distribution hub, headend...or whatever you're calling it. Save yourself the $100 service call and return the box. Again.