At the end of your table for mainWrapper, you have this:

Code:
</a><a href="https://www.tucson-creative-ventures.com/index.php?main_page=logoff">
I believe you'll find that is the source of your problems.

You have a heck of a lot of unnecessary code - empty divs and the like. You might consider running a page through HTMLTidy (after you've validated it).

BrandTim