Sometimes when I go to play a song on my iPhone, it skips over it entirely and goes onto a song after it in the list.
The same happens when I try and play it in iTunes directly from the device - it gets a exclamation-mark-circle icon to its left when I try and play.
The songs have all been copied on by drag/drop from MP3 folders, so I suspect the copy process didn't completely properly. Is there a way I can find all these songs so I can re-copy them? (Trying to copy the entire album over again creates duplicate entries.)