I haven't had the boot up problem either, but my email to Yamaha was for those that had the SX900 actually freeze at the logo, supposedly from using Favorites. I didn't want it to happen to others, including me I'm starting to think that those few affected either tried something crazy, or they just got stuck with a lemon. It happens.

I'm glad you reported the delete registration / reboot thing, but there might be a reason why the SX900 does that. Maybe it's just a cautious aspect of the keyboard that protects the software from infectious registrations.

Either way, it's good to let them know. We'll see what happens