Reinstall drivers to newest version...
------------------------------------------------
- unplug all USB-adapters at USB-ports
- remove all FTDI-liked drivers from Control Pannel-Add/Remove Programms (MECo, tieCAR, FTDI etc.)
- use FTClean utility and remove drivers with FTDI-PID
- use FTRemove utility and clean up debris of FTDI-liked drivers anywhere in windows
- restart PC
- plug USB-adapter to USB-port
- install newest drivers
----------------------------------------------- 
Always use newest drivers path in the future...