I've noticed it in IE 7, 8 and 9 - one workaround is to use the drop-down to the right of the back button to select the page you want to go to, or use site breadcrumbs to navigate back up the site.
The only other thing I can suggest is an adblocker. IE7Pro works for IE 7-9, but not 10. There are others, paid for and free.
SD