I was playing around with an Arduino Nano Clone and programmed it via an USB <-> RS232 Adapter. At first it worked fine, but then the Board was not recognized. I was surprised because this Driver which Bricks the those fake FTDI chips has been withdrawn and FTDI changed their approach. At the time i was Running Win 8.1 and i couldn’t find a complete Fix which did work for me. This is what worked for me and Maybe it works for you too. I zipped the needed and modified Files the download is here.
Steps To Repair
1) Uninstall the Driver (Win + Break / Pause -> Device Manager -> Right click on the unkown Device -> Uninstall)
2) Install the new (old v2.08.30 ) Driver. I modified the inf files to work with the 0000 PID (Right click on the unkown Device -> Search for th Driver on PC -> Browse the List of Devices -> Click on Storage Device and browse to the modified Drivers). Howto to Change the Inf Files in German ( Heise.de )
3) If Windows doesn’t want to install the unsigned Drivers you will need to Disable the Driver Signature Verification (Win + i -> click on the Power Button -> shift click on Restart -> Troubleshoot -> Advanced Options -> Startup Settings -> Restart -> Hit F7 when on the Dialog screen -> Repeat step 2). Here is a full Guide
4) Install FT_Prog (Version 126.96.36.199 worked for me) open FT_Prog F5 ->USB Device Descriptor -> Custom VID/PID select Custom VID/PID -> Change Product ID to 6001 -> Ctrl + P
FTDI Drivers and FT_Prog