STR:

1) Enable JS console in Firefox
2) Show RHQ Dashboard
3) See the error:
"uncaught exception: Syntax error, unrecognized expression: [@src$=.png]"

It's in jQuery PNG fix plugin - pngfix.js line 45:

jQuery(document).ready( function() {
  jQuery('img[@src$=.png]').ifixpng();
});