Your user Agent says you are running Firefox 4. Can you check what version you are actually running by typing about: into your address bar and pressing enter?

hello, your useragent (the information the browser sends to websites to identify its version) - apparently mistakenly - shows you're on firefox version 4. please refer to this article in order to reset the user-agent settings in firefox: How to reset the default user agent on Firefox

Many thanks for your swift response. Solution appears to be working but only time will tell. Regards Alan Brewer.