RM browser plugin - has it changed between 4.0.3 and 4.0.5

Our bussiness PC's (windows 7) are pretty welll locked down in that users cannot install apps etc on them. Basciallly anything that required admin rights i snot allowed.

In that regards, we have had the JAZZ 4.0.3 RM browser plugin for editing graghical artifacts packaged by our IM group and installed on these locked down hosts.  Prior to upgrading from 4.0.3, this worked as users would get all the graphical editing objects in their browser (IE 9).  

We recently upgraded 4.0.5 and now the browser does not recognise that the plugin is installed when trying to edit a graphical object and tries to install it which subsequently fails due to lack of user permisions (no admin rights on the OS) .

Can someone tell me if these plugins changed between 4.0.3 and 4.0.5 requireing another install/reinstall? I'm trying to determine if its the jazz app or some OS/IE change that caused this to functioanlity to break.