Well, actually the preview pane was not causing the error. It was the java-script inside my header.php, that was meant to do that – very successfully indeed.
I don’t know of a solution else than disabling all scripts when loading the preview. You don’t really need javascript working in your preview page anyways, at least I don’t.
So maybe you could consider this to be a design error. Maybe there is also another reason for the edit page reloads, I personally fixed it by removing the <head>-script.
