After updating to Mac OS X v10.5 (Leopard), when you reset Adobe Bridge preferences using the 3-key reset method, Command+Option+Shift, the reset preferences dialog appears but preferences are not actually reset.
When you reset preferences, Bridge locates its .plist file (com.adobe.bridge2.plist), deletes it, then forces the preferences to be flushed (since the .plist no longer exists.) Under Mac OS X v10.5 the preferences are not being flushed. The next time the preferences are written, the .plist file is recreated with the new value plus all of the old values still intact.
In Mac OS X v10.4.x, the .plist was recreated with only the new preference.