This issue also occured for me. We fixed it by clearing out the internet browser cache (on each browser affected) then closing it and trying again. Be sure to remove all cached data and cookies for all time. Hopefully this will solve your problem.
I agree that the IE plugin is great for consistent rendering, but there are many reason why AJAX is better. Most importantly it is browser agnostic and faster - not to mention client-less. The mobile aspect is a small reason to use AJAX and even with its quirks it is by far better than the performance of the plugin.
Screenshot fo IE9 cache clearing settings:
Chrome cache clearing settings: