Preface - a few weeks ago I successfully installed Windows 7 on my 2009 MBP. Partioned through Boot Camp Assistant, installed Windows 7 via self-created DVD (from an .iso), then installed the extra downloaded drivers from an external HD once I first logged into Windows 7, and everything worked fine.
Today, I got a new 13" rMBP and I am having far less success. I have a USB thumb drive with the Windows 7 64-bit .iso, and a different USB thumb drive with the downloaded drivers (I've also tried the following process by using a USB hard-drive with the downloaded drivers on it's own partition, but that shouldn't work any different, I don't think?). I boot up from the thumb drive with the .iso on it, get the Windows 7 "install now" button, but then get the error:
"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. Note: If the Windows installation media is in the CD/DVD drive, you can safely remove it for this step".
If I click OK at that message, I get "No device drivers were found. Make sure that the installation media contains the correct drivers, and then click OK."
I've poked around on the discussion boards for the past hour but haven't found any solution that has worked. I've tried the install when I just have the .iso USB drive plugged in, I've tried having both that and the downloaded drivers USB plugged in - same error both times. Conceptually, I understand that the Windows 7 .iso wouldn't have any Apple specific drivers on it (and that's what the extra downloaded drivers are for), but I clearly can't install those drivers until AFTER Windows 7 is actually installed. Is it because I'm installing from a USB drive and not from a DVD that I'm getting this error? I have access to an external Apple SuperDrive so I suppose I could burn the .iso onto a DVD and then try to boot up off of that, but would that truly make a difference?