Problem with permalinks in "Classic Theme"

That sounds actually pretty strange.
If you are using Firefox with the Firebug addon (for CSS + JS inspection), you may check if the URL of the header is correct.

You may want to watch this : http://www.kristarella.com/2009/02/how-to-use-firebug-for-css/

There are not so many easy other ways to check if or why your image is missing 🙁

You could check the source code of the page, find your image (is it included as <img> tag or via CSS ?) and then chekc if the image is missing : copy the HTML code and try to open the image in a distinct window or tab.