I bought a Lilypad Snap thingee from sparkfun a while that had the demo sketch, but no bootloader. Didn't break out the SPI pins so no way load the bootloader without a special TQFP adapter.
Do you have a working Uno? Can set that up as an ISP and put a bootloader onto your Promini's:
Could also try updating the FTDI driver:
http://www.ftdichip.com/Drivers/D2XX.htm
Win x64-bit (or 32-bit, but not likely with newer machine)
Another member reported success with this yesterday.