Are you seeing ads after our most recent update to AdBlock for Firefox? If so, open your AdBlock menu (the AdBlock icon in the upper right-hand corner of your browser), select Filter Lists, and make sure EasyList is enabled.
We inadvertently disabled this filter list for some users during the update. We're sorry about that! A fix has been rolled out so it won't happen on future updates, but affected users will need to re-enable EasyList. Learn more about AdBlock filter lists and why you need EasyList enabled here.