FYI-I recently upgraded to Skype 4.0 which has a firefox add-on. I started working on a paper and was flabergasted when when zotero wasn't working but seemed to be installed without errors. then i noticed that both the Skype and zotero buttons had disappeared but not the cooliris button. When I disabled the Skype plugin and restarted firefox the zotero button came back. It wasn't just a problem with the button, but the shortcut key ctrl+alt+Z would not open it either when the skype addon was enabled. I don't know if this is a zotero problem per se but I wanted to let the zotero people know.