Yes, it's happening now with my FP1U.
It seems to reboot when it's fully recharged although not every time.
This wasn't really bothering me too much until yesterday when after the reboot, the screen went black and chinese script appeared and before I knew it, factory settings set in and all my data lost! Can't even make a phone call as it won't recognize SIM 1 which I use most of the time.
Really depressing. It was great while it lasted.
Doubt if anyone will read this post.
Am now trying to decide what to do.
Whether to go for the FP2 or go for one of the unethical phones .....