I confirm this problem - more precisely, You *can* save file edited as root, but reboot occur, when You try to "save as" - it happens all the time, exactly before moment, when prompt for location should pop-up.

I've also installed latest Busybox power, so I'm also not sure which one - kp48 or busybox - cause this oddity.

// Edit

It's possible, that people with R&D mode enabled, won't meet that problem (watchdogs disabled). So, please write about Your R&D mode status, while confirming/denying this issue. I got R&D mode off.

Also, when gaining root in xterm via "sudo gainroot" running leafpad ("leafpad", just to open blank), then choosing "save as", leafpad crashes with seagfault. I don't know if that is related though, haven't tested this exact method before.