Pop-up Photo Irregularities

Hi All

I have pages with layers on which are pop-up photos. These tested fine when the site was published locally; but after the site is published online, I notice on occasion that IE does not pop-up a particular photo and instead shows it on its own page full screen. I then have to press the back button to get back to the previous page. Strangely, this only happens irregularly. Is it an IE 9 browser issue? The problem does not occur in Firefox. Weird.

As an extra thought regarding this, I think the issue may have to do with the insane time it occasionally takes for IE to load page content. If the page is not fully downloaded, and a pop-up is clicked, it merely opens in the entire page and not as a pop-up.