iTunes PLAY/PAUSE Will Not Work After 10.5.4 Install

I have just installed Leopard 10.5.4 on my iMac G5 and iTunes player will not work. When I select a song, it will show in the player window, but, PLAY/PAUSE button will not function. I have checked iTunes Prefs and see nothing there that is not correct. I am able to navigate throughout iTunes and everything seems to work as before EXCEPT Play/Pause. (Actually, I don't know about PAUSE since I cannot get PLAY to work).

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