Hold down option key while restarting Bridge and choose reset prefs.
If this is not possible or not working Quit Bridge and go to the user library (hidden by default, use menu Go with option in Finder) and in the preferences folder delete the Bridge plist file manual to the trash:
user / Library / Preferences? Adobe.com.Bridge(xx).plist
Then try again with again option key and reset prefs.
Otherwise create a new user account for testing and check if it works from there. If so consider using the MacOSX recovery disk to repair your user account. Read the instructions carefully before acting and back up al important files and settings first