firefox is nice for webdevin’ but it can consume a lot of memory under certain circumstances (e.g. while loading a 12mb+ print_r output of a debug_backtrace). while this happens, firefox under windows consumes very much memory si that the system starts to hang. this little commandline came to my rescue lately, just execute it and firefox will be closed then:
taskkill /F /IM firefox.exe
tested on windows xp. the /F switch forces to close the app and the /IM switch names the module name, in this case firefox.exe.