Also,
If you're running Mountain Lion (Mac OS X 10.8), this is what worked for me:
goto the support link: http://support.apple.com/kb/HT1747?viewlocale=en_US&locale=en_US
Note: If the mac tells you that you can't remove iTunes, you will have to do a "Get Info" on the iTunes application icon (command + "i", or right click on icon and select "Get Info") and change the "Sharing and Permissions:" (click on the lock at bottom right, enter your administrator password, then add adminstrator (use "+" sign on left) with "read & write" privilege for the "admin" name, so that you can remove iTunes prior to reinstalling it as described in the support link. Make sure you follow the steps as described in the support link. (However, it is not necessary to delete everything from the trash, as described in the support link, at least prior to completing the re-install, in case you screw things up and want to go back to what you had).
At least for me, when I reinstalled iTunes all the preference settings were nicely maintained. Good luck.