Hi All,
I'm the latest victim of these counterfeit chip =(
I contacted FTDI and they replied this is a counterfeit chip without showing any evidence 
I'm sharing here how I managed it to work again.
Once you connect the counterfeit chip in Windows 8 or Windows 7 with drivers from windows update or the official driver it will first detect the device and re-write the PID to 0000. After that it will not work at all and it will be detected as an unknown device. You can't change the PID in the .INF files in the official driver, it won't work.
The workaround:
You need a Windows XP system or a Windows XP virtual machine running in a Linux or MAC system. Please note that it won't work in Windows 7 or Windows 8 VMs because it will detect the device as unknown device and it will not allow it to attach it to the virtual machine. I had Mac and it happily allow it to attached to the Windows XP virtual machine. Run your VM or the Windows XP system and attach the USB device to it.
Download the official driver for Windows XP from FTDI site, extract it and edit both the .INF files. Find and replace all 6001 to 0000. Now this modified driver will work with your counterfeit device in Windows XP. Update the drivers from device manager for the counterfeit chip.
To program the PID back to 6001 you need to download M_Prog or FT_Prog utility from FTDI website. Download any one of them and run it. Scan and Parse for the devices. It will show the device attached to your VM or the System. Now change the PID back to 6001 and reprogram it.
Dont connect it to Windows 8 or Windows 7 system now. First delete any existing driver from your system, there is a utility available in FTDI site to remove old drivers. Second find any old FTDI driver from internet, just google it, you will get few links. Disable your internet connection in your system and now connect you device and update the drivers from the downloaded driver. The device will work happily with the old driver.
Still I'm finding a way to disable the eeprom write in counterfeit chip 
if someone know please share.
Thank you.