I'm using FCP 7. Inexplicably the effects tab disappeared. I've read other posts that suggest hitting the command and 5 keys together. This has not restored the tab for me. I also tried opening new projects. This too did not work.
I kind of think there's something you could easily do in order
to fix your problem but since I can't see what you are doing then... [trash preferences|http://www.digitalrebellion.com/pref_man.htm] (and back them up if you wish). This should help.