iPod Classic doesn't show music

It's a 6th gen. 160GB model that I've had for several years without any problems before. Since a few days ago it has started crashing iTunes when I plug it in, meaning I can't sync. By force shutting iTunes I have been able to format the disk and reinstall the OS via iTunes (which doesn't mind the formatted device), and it will sync as usual.

However the real kicker is that when I disconnect the device on finishing the interface shows no music or any contents at all. Plugging it back into both iTunes and Windows Explorer shows that it is full of music files that I can open and play using it as a HDD, but the device interface says there's nothing there at all.

Several reformats, fresh installs and restarts of everything I can think of already tried. Any ideas?