Play lists randomly disappear and reappear

Recently my iPod classic 120gb has started to play up.

Usually now iTunes will freeze if I connect it. I had reformatted the drive and added multiple playlists but now it claims to have 1 playlist and if I try to access that playlist nothing happens. It shows 80gb free which would be OK for the playlists I had loaded

I had left it alone for a few weeks and it then showed all the playlists I had loaded! Trying to put it into diagnostic mode they have vanished again :(

I will be happy to replace whichever part is bad if anyone can diagnose it

Thanks for any help

Jerome