Howdy samjco,
Unfortunately there are no shortcodes to cure ajax problems. There could be a million reasons for this. To assist you with fixing it we really need to see it in action. Can you link to the page where this is happening? Or, is it a local site? It sounds to me like this is a theme conflict with a custom theme’s AJAX loader, however you state the issue persisted when you enabled the 2011 theme. Did the problem persist with 2011, or was that checked by mistake? If not the 2011 theme, what theme are you using?
Please let us know the answers to those questions so we can assist you better. Thanks!
– Brook