Firefoxを起動するとかならずエラーがでます。最新バージョンにグレードアップしても同じ。メッセージを消す方法を教えて下さい。ＩＥなど他では出現しません。
The following extension(s) are required by Page Speed
and must be installed before it can run:

- Firebug (http://getfirebug.com/)

To profile a page with Page Speed:

1 Start Firefox.
2 Select Tools > Firebug > Open Firebug.
3 In the Firebug window, select the Page Speed tab.
4 Navigate to the web page you want to analyze. Wait until the Done message appears on the browser status bar and the progress bar disappears. For pages with streaming video, which don't show the Done message, wait until the video begins to play.