Weird behaviour in IE compared to Firefox

Hi all, i have set up a quick site for a friend of mine,(pisceanprincess.com/blog/) and she has gone and added content etc.. in firefox everything displays perfectly, home page, about me page and the categories.

however in IE the sidebar where the categories are displayed do not load, nor does the search box. Also if you click on the about me page top right, it will display only the post heading. But if you were to open both the pages in firefox they would display correctly.

This is driving me nuts, it all worked fine when i handed it over to her, im not sure where things went wrong..

I hope its an easy fix for someone else.
thanks in advance.