I've just been informed that the Japanese soundtrack to the new Ponyo DVD and Blu-Ray are perfectly fine, without the Disney remixed song at the end. I appreciate the help in taking the time to look, which I was unable to do because my PC's DVD software is a hideous mess.
I've deleted the post I wrote late last night, since it's no longer needed.
Now can someone tell me why I can't play movies on my computer? Is Power DVD a bug-ridden mess, or is this Windows XP's fault? Goodness knows I'm not about to reinstall the operating system yet again. No thanks.