いつのタイミングだかで、なーんかvimperatorが悪さしてタブ表示が変になったなーと思ってたら、
WARNING: Vimperator 2.0 and the TabMixPlus extension have some serious compatibility problem. We advise to just uninstall TabMixPlus as most features are already provided by Firefox anyway now. Or you can download version 1.2 from below which should still work with TMB.
TabMixPlusとの相性だったのね。Firefoxがやたら不安定になる。
