Hello Lenora,
With the latest update to Firefox (V52) support for Silverlight was removed.
The solution to this is to use Firefox ESR (Extended Support Release). This is Mozilla's release pathway optimised for stability and is therefore preferred in many business environments. Naturally, security isn't compromised, while stability is enhanced. This means that Silverlight will continue to work in it.
You can find the download page for Firefox ESR at https://www.mozilla.org/en-US/firefox/organizations/all/
To install, you just need to select your language and operating system. The version number for ESR is the same as on your 'normal' version of Firefox. After you install it all of your bookmarks and passwords will still be there.
From the user's perspective, Firefox ESR won't look or act any differently to what you had installed before (other than Silverlight will now run in it again)
We have updated the message that you were seeing to give instructions on how to proceed. There is now also a message on the front page of the gateway with a link to our forum post with more information (https://eppi.ioe.ac.uk/cms/Default.as...mp;scope=posts)
If you are still having any issues please let us know.
Best regards,
Jeff