Running Snow Leopard 10.6.6 on a Macbook Pro w/4Gb of RAM, Parallels Desktop 6.0.11992. Trying to install Windows 7 64-bits, but as soon as the installation launches, I get an error message: A required CD/DVD drive device driver is missing. If you have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now. I can only click Browse, Ok, or Cancel. Why? What am I missing? Thanks! Jacques