Having troubles with Firebug 1.1.0b12 (currently the latest official beta release) and Firefox 3 beta 5? I know you are (it tends to hang, the console doesn’t work properly, etc.). Solution is to grab the lastest 1.2 beta release from http://getfirebug.com/releases/firebug/1.2/ (current version I have installed and verified working is firebug-1.2.0a21X.xpi).