I had a problem with iTunes in my new Tiger 10.4 install today.
Every time I started iTunes it would quit before the main window appeared.
I did a reinstall, repair privs, etc, etc no joy.
Then I deleted the Plug-in and scripts that I had, and then iTunes works OK.
I am on the same version of iTunes that worked with the plug-in / scripts before, so Tiger must be upset about something in there.
Anyway, if you have this problem try removing the Plug-ins and scripts
Ian