Problem Installing Prolific PL2303 in Windows 7
Installing driver for Prolific USB adapter can be problematic. The cause maybe because counterfeit chip, as noted in http://www.ifamilysoftware.com/news37.html
“What appears to be happening is that there are a ton of counterfeit “Prolific” chips coming from China and getting the correct driver installed is like playing Russian roulette. Prolific talks about this on their web site and I’m betting are as frustrated as we end users.“
In my case, my installation problem is solved by reading a note in the following forum http://www.sevenforums.com/drivers/4476-prolific-usb-serial-driver-2.html
“This is how I got to connect my older Nokia 6103 to sync with Outlook in Windows 7. Surprisingly it was not the latest build of the driver found on the prolific website that was compatible with Windows 7 that worked for me. I went here instead: Windows Vista driver for prolific chip USB Serial Adapters and got the vista version. Even though it did not ask for a reboot, I did so because of the nature of serial ports and it installed successfully. It still did not recognize the phone until I change the com port from no. 1 to 3 that it did work. Cheers! “.