To correct the error, you will have to download the driver again by following these steps. Once you upgrade your PC to the latest Windows version your Prolific USB to Serial Driver also updates to the latest driver software and if the driver is not compatible with your Hardware issues may arise. Unfortunately updating your drivers can cause this kind of error especially if your latest update does not work too well with your hardware. Updating your drivers often work wonders for your system because it makes sure that it runs on the latest features that guarantee maximum functionality. Part 2: Solutions to Fix Prolific USB to Serial Driver Not Working Solution 1: Roll Prolific USB to Serial Driver Back to An Older Version Read on to find quick fixes to resolve the problem. While you can't be so sure what the exact problem is there are solutions you can adopt to fix the issue once and for all. If you are not able to connect your device to your PC using a USB to Serial adapter it may be that:

Part 2: Solutions to Fix Prolific USB to Serial Driver Not Working.

Usb serial controller d win 7 x64