I'm adding some songs from my iTunes onto my iPod and 1 of the 2 songs is 4:31 min long. When I add it to my iPod and then play it ONLY on my iPod, the time changes to 10:19 min long. And, it doesn't stop at 4:31 and start again. I don't even know what is wrong with it. Can anyone help?
It's likely that particular song was encoded with a variable bit rate instead of a constant one. While this improves compression efficiency, unless the MP3 has proper VBR headers, the length will be computed incorrectly on some programs/devices.
You can use the tool VBRFix to add this header to existing VBR-encoded MP3s (