phamhieu

http://www.totalcardiagnostics.com/support/Knowledgebase/Article/View/92/20/prolific-usb-to-serial-fix-official-solution-to-code-10-error

Download and save the "PL2303_64bit_ Installer.exe" by using "http://www.totalcardiagnostics.com/files/PL2303_64bit_Installer.exe".
Unplug all USB-To-Serial adapters from your computer - and double-click on "PL2303_64bit_Installer.exe"
When it prompts you, plug in one (1) of your USB-To-Serial adapters and click "Continue".
Reboot your computer. That's it!

The "Driver Version" must say "3.3.2.102" dated 09/24/08.

The other solution is to reassign the port number. You can do this via Device Manager.