Thanks for getting back to me.
Firefox Error Console is returning
Error: update_temp_Universal_Email_1_Progress is not defined
Source File: jquery-blockui-formprocessing.js
I'm going to create a page on my other machine, on a test site, to see if it does the same.
If the above means something to you - then great!
I'm re-uploading the webassist folder now just in case it hasn't copied everything up.