What kind of ads are they? Could be a browser formatting issue with IE9 which may be caused by a corrupt cache. Does using CTRL+F5 correct the issue? You may have to completely clear out your old cache and cookies? The free
CCleaner can do so with one click, and does a more thorough job than just using browser controls itself.
Another way to determine if its a browser issue is to check using a different browser such as
Firefox. You can install as many browsers as you want. Even run them all at the same time.