What project did you use. This might configure the FX3 with a new vendor/product ID and if this ID is not in you driver .inf file the driver will not load.
Go to the device manager select the "unknown device" right click "update device" and select the cypress driver and that should take care of your problem. Also ensure you have allowed unsigned drivers to get loaded.
I'm working on WindowsXP. I solved this problem by editing the *dscr.c source, changing the Product ID line from 0xF0,0x00 to 0xF3,0x00, and it worked fine.