Hi, I had a similar problem, although I was trying to connect a FT8U232AM(not BM), to a PIC16F628A, and a mac rather than windows. The symptoms were similar though: it recognized that the device connected, but couldn't connect to it or use the virtual serial port. It turns out that you do need to add a pullup or pulldown resistor to one of the pins of the FTDI chips that normally connects to the EEPROM. I don't know the details by heart, but it is described in the datasheet or one of the application notes. You may have to look for it in the documents, because I do remember that it wasn't described in all of the documents and I missed it the first time. It may well be similar for the BM chip you are using. Hope this helps. PS, let me know if you can't find it. I'll check out the circuit I made and tell you what I did to solve it.