I had the same problem with my Nano when I first got it. Resetting everything worked for a while, but then it started having the same issues again. When all this was going on, I was trying to sync it to Windows. So one day I decided to just give it a whirl on my MacBook and I haven't had a problem since then. Not sure if it actually had anything to do with the OS, maybe the third time was the charm. I've reformatted my Windows machine since then. I'm beginning to think that since my wife uses the Windows computer that perhaps spyware or something else was causing the problem. But anywho, that's just my experience with it.