I'm trying to load music on to my mom's 4 gig 4th generation nano. Since it only has 4 gigs and I rip my music as 320 kbps aac files, I'm trying to use the setting that converts music down to 128 kbps aac files while loading them. Every time I try, it says the files cannot be found. However, when I try to load them at the full 320 size, it does it without issue. Any ideas?