I see right away what the problem is ...
Your site was created with Microsoft Office.
That rendering is not valid HTML or XHTML for
anything other than Internet Explorer (a Microsoft product).
It creates terrible coding and extreme compatibility problems.
I hate to say that you need to start all over again, but that's
what you need to do. Use Dreamweaver if you need a WYSIWYG editor,
or use FrontPage (gasp) if that is available. FP is bad too, but
way better than MS Office.
The very best approach is to find a free XHTML/CSS template that
you can download (search for free CSS templates using Google).
Customize a CSS template with your own graphics and content.
This of course is all done by hand, using Notepad or Wordpad.
Sorry I don't have a better answer.