I recently changed my header image to a different sized image (900x390px to be exact), and now its not showing up.
Any help would be greatly appreciated.

Can you, please, give a link to your forum for let us see ourselves what could be wrong ?
But it seems ( at the first sight ) to be a template issue anyway ... Did you try another style ?

Thanks for the reply but now the site shows up blank. I'll have to create a new thread so this thread is closed for the time being.