I-Phone Question About it's Music Features

My brother has an I-phone and when using the music feature synced to the I-tunes music library much of the cover art is scrambled. About half of the music has miss-matched art work. Does anybody know what is causing this, there seems to be no rhyme or reason to which songs have the correct artwork and those that don’t. Any ideas, the support groups so far have been no help.

We also have the standard I-pod and all of it’s artwork is correct.