Firefox users have had all the extensions they use in their browser disabled due to the expiry of an intermediate signing certificate a few days ago. They have also been unable to download and use any new extensions.
Skype can no longer be accessed on the Web using the Firefox browser on both Linux and Windows, as of Wednesday morning. The same applies to Opera.
The Guardian Australia says it will be able to protect Mac users from being redirected to other pages when they visit its website using the Safari browser, but it will take some time to do so.