Memory-Map gives this error message if it is unable to open or use the currently selected COM port.
If you are using a Garmin GPS with a grey screen, and it is connected by either a serial or USB cable, please download and follow the steps in our Serial Garmin troubleshooting guide.
If you are using a non-Garmin GPS unit and have selected the wrong COM port then you will also receive this error message. Make sure that the selected COM port is correct by checking in the Windows Device Manager under 'Ports (COM & LPT)' (see the Windows help file if you are unsure how to find Device Manager).
Also, if another program is using the COM port at the same time then Memory-Map will not be able to access the COM port. Make sure no other applications are using the same COM port before starting Memory-Map.