"Select CD-ROM Boot Type:" error during Windows install

Which version of bootcamp 4.x do I need to install Windows 7 (64 bit) on an iMac7,1 with Yosemite?

Specs: 64 bit Core 2 Duo, 4GB, 16GB Flash, optical drive, Windows 7 install DVD

Everything goes fine until during the install process Mac reboots to install windows then:

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Select CD Rom boot type:

I can't enter anything because keyboard and mouse are unresponsive and I assume the correct drivers were not loaded.

iMac is mid 2007 24" 64 bit (says profiler/other internal monitors). Have downloaded various boot camp versions, followed documented instructions, stood on my head and spit nickels, and still get same error (Select CD Boot ROM type). Made ISO file with Mac Disk Utility (create and change .cdr to .iso) Didn't work either.

After further review, seems that I misread Apple support table which show this model uses Boot Camp 4 for 32-bit Windows 7. Genius - bought install DVD for 64-bit :-o So I guess that's why it won't install.

Going to try suggested method of creating ISO from W7 store-bought DVD on Windows machine just for giggles and see what happens. Then probably go buy the correct DVD for 32-bit :-( Thanks for the info :-)