I looked at your source code - you have a few unclosed DIV tags......that will throw off your layout and styles.
Also, equally as important, you have several instances of class names and ID names being the same - this is invalid CSS and can cause problems.
First print out the source code for your index page as displayed in HTML, then go through it carefully and mark where your DIVs open and where they close so you can identify which ones are left unclosed, and be sure you close them where you want them closed, don't just stick in some </div> tags at the end.
Second, look more closely at how you are calling your styles (for example right at the top of your code you have <div id="navtop"> and a few lines down you have <ul class="navtop"> ).....You should rename one or the other and modify your stylesheet to create the correct style for the new class/id name you're creating.
I imagine that finding and closing the open DIVs in the right place and cleaning up your CSS will go a long way to fixing your problem....