My MP3s cannot be played on this iPod?

I just bought the newest-generation red 16GB iPod. I have a song that was NOT purchased in iTunes but that PLAYS in iTune, and which "was not copied to the ipod because it cannot be played on this ipod."

The song is an unprotected 160 kbps 44.100 kHz MP3 file--looking quickly I cannot tell in iTunes if it's variable rate.

I read some other forum questions and tried re-creating my iTunes library ( http://support.apple.com/kb/HT1451) to no avail. I've also seen suggestions for converting the file format--especially when it comes to video, but also for some reason when it comes to MP3s. A) This seems silly, especially in light of the fact that B) the only option I seem to have is Apple Lossless, rather silly considering I'm converting from the lossiest of file formats.

To reiterate--this music was NOT bought in iTunes, then burnt and imported. This is a regular old (and I mean old) MP3 (MPEG-1, Layer 3) audio file.

Any help in keeping my temper in check and chucking my now largely useless iPod (it's happening with a LOT of the music I want to import) out the window would be MOST welcome. 🙂

I'm running build 8.0.0.35 on Windows Vista.