Hi Jim,
Just a thought, but could it be that your host goes down monentarily the times that you don't see the banner? I'm only suggesting this because it appears the banner image is hosted on your own site and sometimes hosts do have "blinks" where a site is inaccessible, but only for a very short period of time (seconds or a minute).
~ Teli
P.S. Some people may not vote, even though they're viewing your entry or this thread, because it may be their first time here or haven't logged enough times to give you a definitive answer of yes or no to seeing the banner
every time.