No wizard

Thickbox (?) covers the pages, rotating "loading" image, but no wizard arrives...

Nothing in the Drupal logs, but Firebug returns the following:

self.html(res.responseText).evalScripts() has no properties
e(XMLHttpRequest readyState=4 status=200, "success")jquery.js (line 2)
e(undefined)jquery.js (line 2)
[Break on this error] eval(function(p,a,c,k,e,d){e=function(c){return(c<a?"":e(parseInt(c/a)))+((c=c%a...

Any advice anyone?
Thanks!