I just had to deal with one of these today. It was a last minute "by the way can you check this before you go" item. Client still uses ipod classics (has dozens of them for houses/boats/cars/planes etc that he keeps synced with all the same content). It was barely working then not at all like it locked up. I tried power cycling it and a voodoo prayer and it still didn't work.

After consulting with our programmer i did a firmware update and now its working without any issues.

My uneducated guess is that people with problems are updating the firmware on the device frequently but not the NSP-1.