I have exactly the same problem with my own site (set up for my wife’s business) using IE 8.0.6001. The header image appears blank in IE8 but is fine in Firefox, Opera Mobile and IE9. My IE emulator shows no header image in IE8 mode, but the header image is visible when emulating IE6 and 7, so I think this is IE8 specific.
For now I’ve changed the theme to Catch Box (I like Catch themes because the CSS is so easy to add to) and customized the CSS to make the menu look like Everest, but would really like to see the simplicity of Everest if possible! Tried some horrible CSS hacks to fix the header position – the header image appears but looks pretty hideous and can’t get the CSS to apply to IE8 only.
Hope you can help!
David.