Hmmm... You are syncing over ethernet. It might be worthwhile to have a live hyperterm session up and running while you sync to try and catch any console errors. I have not tried this, so I do not know if it will work, but it might be worth a try.

When you say the player is rebooting, is it going through the complete reboot (tux waving with boot logo, full linux boot) or just the player application startup with the small logo and messages?