header pictures not showing up in single posts

I am new to wordpress and have been trying to do some tweaking to the default theme. I put some pictures in the header as links. They aren’t working right in Firefox right now, but I am going to work on that later. Right now my issue is the fact that they are working fine in IE except when you look at a single post, then the pictures won’t load. Any help that you can offer would be greatly appreciated. The site is
musiqcritiq.com