I am not sure what might turn this off but try menu, settings, television and disable interactive TV and Recommendation for you.
I know I always hated pop up of these kind on a different vendors DVR and so set both of them to disable when I first went through the settings menus. Perhaps that is why I never saw the mentioned pop up.
I have those settings and I did get the on demand spam twice, once on my 7232 when I prssed the DVR button and on a 7100 when I pressed the menu button. Never touched the On Demand button.