Can't help you without more information. We don't know what your code looks like, we don't know what the webpage looks like, and we have no clue how you're hosting your site.
We're going to need a lot more information from you in order to even begin troubleshooting the problem. What you've given us so far is akin to, "My car is making a noise -- what exactly is wrong with it and how much exactly is it going to cost to fix?" Please elaborate greatly.
Also, your problem seems to be more along the lines of HTML development with Google's AdSense -- unless there's something Mac-specific that's causing the problem, this may be a question better posed on the Google AdSense forum.
