When I activate Adblock Plus, several menu items disappear and statusbar items from other plugins also disappear, not to mention the ADP icon which is nowhere to be found despite that I have it checked on the ADP menu. It's not necessary to uninstall ADP, simply disabling it and all these things come back. I've reported this to mozdev.org, but upon reading other people's comments it seems I'm not the only one with the problem