I recently upgraded to iTunes 10 because I was dying to try Ping. Let me rephrase that, I upgraded to iTunes 10 because I hate it but have an iPod, and I do love the Store. Anyway after upgrading, I found that some mp3s couldn’t be played anymore. Not in iTunes, nor on my iPod. Googling around only led me to two discussions on the Apple forum. But it seems quite some other people are having this problem: the biggest part