I was checking mprog utility from ftdi with my decimila connected. "Scan for available devices" showed that they are 0 empty devices and 1 programmed on my system. I played a bit after pressing "Read and parse" changing the vendor, etc, then I have pressed "Cycle device" button and my decimila stop working. I haven't upload anything!
Now everytime when I connect the decimila, windows says "unknown device" and with usb viewer I see: "'0x00" for all that of that device with "DeviceFailedEnumeration" message as device label.
What happened?
Futher more, I can not even reprogram the ftdi chip (Arduino Playground - FTDI) because mprog does not find any device now . I have already killed a decimila ftdi connecting by error 10v on some point, but it was fixable with a lot of work (desoldering the ftdi and resoldering it with a regular soldering iron), I don't want to repeat that experience! :-/
If you were messing around with the vendor etc, windows might not know what to do with it. I used MPROG to reprogram some of the chips but I left the vendor alone and just re-assigned the device ID so instead of that annoying 'A7006' serial number they show up as just one (makes programming a bunch of them about 100 times easier).
I'd say check the device manager and see if there are any unrecognized devices. Try to point it to the FTDI driver if you can.
I played a bit after pressing "Read and parse" changing the vendor, etc,
Looks like it's possible you reassigned the vendor and device codes. Like Sterling suggested, look for any unrecognized USB devices on your system. See if MPROG will find it using the vendor ID on the unrecognized device.
Try and use this info (specifically the vendor ID and product ID) to see if you can make mprog a) talk to the device, and b) program the correct vendor and product IDs (0403 and 6001, I think).