Since late Friday night, an expired certificate caused all add-ons on Firefox to be disabled.
With Adblock Plus being one of the favorite add-ons for users world-wide, this hits us hard. But we have absolute confidence in the open source community behind Firefox to get this fixed as soon as possible!
There is nothing you can or need to do, other than wait for Firefox to update, which will most likely happen automatically.
So in the meantime, stay strong when faced with a pop-up, a screaming flash-ad or an annoying banner while you browse the web.