Also, for the Japanese titles for songs, it appears as boxes or question marks. Before this, the japanese characters were fine. I have tried installing the japanese pack from windows but it didn't work. Also, when i go to japanese websites, the characters are fine. So why is it only itunes. is there any way to fix this?
From my understanding, if it plays on quicktime, it should work with iTunes.
Also, try converting it into MPEG-4; http://www.mediaconverter.org/ (I highly suggested actually downloading it instead of doing it through the site- it's much faster and easier to do that way)