Nokia N900 :: Unknown Album When Transfer Music?

I seem to have problems copy and paste the music to my N900. I don't have such problem before with my old Nseries phones - like N80, N95, N96, and N97. First, when I copy the entire album, one or a few songs will fall under the "Unknown Album" category while the rest of the tracks (from the same album) are displayed correctly. Second, is the album art. Some albums I have the album art displayed correct at the album listing view. Some don't get displayed but in track view, the ablum art is there. Strange? It is kind of hard to get this to work. I can sort of live with no track repeat, hard to operate playlists, but having my tracks falling into different places are not acceptable. Visit http://www.WilfridWong.com - where all good things are meant to be shared!