Just got the MZ-NH700 and i had a MZ-R55 before that - same problem on both.
On both machines u start it charging by pressing "Stop", so when i plug in and its says "Charging" i leave it - naturally, then i come back in a few hours and the screen is blank - its finished chargin yeh? - Not so when i press "stop" again it says "Charging" again - what the hell?!
When does it stop charging - as in how do u know if the battery is full?