You have a great many issues on that page so it would be wise to start afresh and fix the page as even the validator has to give up because it cannot parse the html.
You will need valid html before you can progress with this so you will need to fix the errors that the validator points out and then revalidate each time as there are loads more that will appear as you start to get the html back into shape.
For example you cannot do this:
<input type="password" class="input-large" name="password" placeholder="Password">
All content in a ul should be inside a list element.
<li><input type="password" class="input-large" name="password" placeholder="Password"></li>
However if you only have one element then its hardly a list so a ul list structure is not correct for that one item. You probably meant to put all inputs in the same list but I don't like using lists for form controls as they are not really lists (although some will argue that they are).
Your navigation is 4 empty divs:
That is a good case to use lists but you really must get some real content in there as at present screen readers and search engines will see nothing at all. If you use background images for menu links then you should use an image replacement technique.
You are using bootstrap so you must ensure that when you create a bootstrap "span" element that the numbers add up to 12 (for the default 12 column layout). e.g if inside a row you have a span3 (div class="span3") then you need another column to be span9 so that they add up to 12 ((div class="span3")) or if nested add up to the parents span value.
You have just used a span element and then absolutely placed content inside it which is much wider than the container it applies to! You must keep to the bootstrap guidelines or you may as well not use bootstrap.
You don't need absolute positioning but use the bootstraps floated spans (note that I am talking about bootstrap span classes and not html spans). For two columns you would just need a span3 and a span 9 inside a div with a class of row. The space at the top of the page for your image could be created with padding-top so that the columns can start in the right place.
Don't give arbitrary heights to the main containers as that will never work. Let the content dictate the height.
I'm short of time tonight but I will have a look back tomorrow and provide some code examples (unless anybody else wants to jump in the meantime :)).