6) Launch Device Manager.
[ Start | Right-click Computer | Properties | Device
You will see one of the following errors in Device Manager.
In 'Other Devices' the 'USB-Serial Controller' is proceeded by a YELLOW warning.
In 'Ports (COM & LPT)' the 'Prolific USB-to-Serial Comm Port (COMx)' is proceeded by a YELLOW warning.
7) Right-click on the entry with the error to open a window and select
"Update driver software..."
8) At the first Update Driver Software prompt, select
"Browse my computer for driver software".
9) At the second Update Driver Software prompt,
"Let me pick from a list of device drivers on my computer"
10) At the third Update Driver Software prompt, scroll down and select
"Ports (COM & LPT)".
11) At the fourth Update Driver Software prompt, select
"Prolific USB-to-Serial Comm Port Version: 184.108.40.206 [7/31/2007]".
You should get a prompt saying that the driver was installed successfully.
You should now see a properly installed Prolific driver in Device Manger.
You can check that the correct version is installed by double-clicking on the Prolific entry in device manager and selecting the Driver tab.
The driver version shown should be v220.127.116.11
12) Remove the USB programming cable from your PC and then plug the USB programming cable back in.
13) (Optional) Reboot your computer.