I too have just acquired a new GMC-300 and find that the clock does not keep the correct time after the unit has been switched to "off". When the unit is turned on again after say 10 minutes, the clock is found to have advanced by only about 30 seconds from the time that was displayed at switch off. This effect takes place every time the unit is switched off requiring the time to be reset after the unit is turned on again. There would appear to be a glitch in the firmware for the clock function.