I'm not sure how your html is marked up, but I assume it is something like in the code below.
I set up 2 test target pages - page1.htm and page2.htm
In the code below, when I hover over 1 image and wait for it to change to the second image, although the target href doesn't change in the browser's status bar, the href does change in the DOM (Document Object Model) to that for the second image.
If I hover on the first image and click it, without moving off it, after it has changed to the second image, my browser does go to the href of the second image.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
ie everytime it cycles it generates a complete <a><img></a> with link and image for that sponsor and insert it using innerHTML which does the same thing as what i had but this changes the link in the bottom right corner in real time without having to move off the banner and back on.
I'm not sure which browser you are using that it did this,.....
The code I posted works in my IE8, FF3.6 and Opera 10.
There were a couple of logic errors in your original code which I fixed. No matter how long I leave the cursor on the banner with alternating images, the browser always went to the href for the image I eventually clicked.