"A required CD/DVD device driver is missing. If you have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now.".
"No device drivers were found. Make sure that the installation media contains the correct drivers, and then click OK."
This was easily resolved with the ISO from;
- http://msft.digitalrivercontent.net/win/X17-24395.iso 2147483647 X17-24395.iso Windows 7 Ultimate x64 English
Please note, if you've already had this issue you MUST remove the Boot Camp partition and start from scratch.
To do this;
1. If you're on the screen with the error above then power off machine --> power back on and hold down option key --> select Macintosh HD partition
2. Navigate to Boot Camp assistant and remove the Windows install
3. Create a new Windows boot USB using the ISO link above.
NB: Last thing, please please please ensure you are using a USB2 pen drive in the USB2 slot and not the USB3 slot.
Let me know if this helps...