please goto fireworks preferences folder and delete these 3 files.
1. Fireworks CS5 Preferences.txt
3. Fireworks CS5 Panel Prefs.xml
you can get access here "C:\Documents and Settings\sheikh.naveed\Application Data\Adobe\Fireworks CS5\en_GB"
WHERE 'c:\' is your drive where you installed fireworks
AND 'sheikh.naveed' representing username, (your will be different).
Thanks! I removed #1 and #3 and it worked!!!