Have you tested the songs to be sure they play ok? Play them to be sure they play ok.

You should not need to convert from mp3 to aac (mp4/m4a). iPod can play mp3 files unless they are in the not so popular or common mp3pro format.

If they play ok, try adding the songs using manual update of iPod; see the lower paragraph here where I advise ucats what to do: http://www.gnutellaforums.com/open-d...776#post129776