Whew! I did more research and fixed it by booting into Safe Boot Mode. (hold down the shift key while the computer is booting)
http://docs.info.apple.com/article.html?artnum=107392
I have no idea what it cleared up that fixed it but it sure did. I feel like such a n00b.
That is basically it. I installed iTunes 4.9 on my 12" Powerbook running 10.4 (Tiger) when it alerted me to the availability of the new iTunes download. After executing the required reboot, the only application besides Finder that will run now is Yahoo Messager. Nothing works. I can not even...