Download the latest Prolific usb to serial convertor from Prolific site.
Make sure you turn off any synch software on Windows 7.
You'll then have to run through the ports to find which one work by trying to connect from MMap while trying all the com's ports; I leave my cable permanently attached and label the port
You beat me to it..... The following was my contribution to that thread....
First connect and switch on the eTrex. Once the eTrex has booted up, using Control Panel, open up Device Manager, look at all the options for USB and Serial Port Comms.
It should tell you what port the eTrex is using. With the eTrex still on and connected, once you've identified the port, open Memory Map, click on the GPS tab onthe MM drop down menus, then select GPS Setup.
Once you've opened the setup menu, check what port MM is looking for the eTrex in and change as necessary to the port that Windows has selected.
