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#1
GPT Win 8 Dual boot installation killed Win 7 MBR boot option.
I've had Win 7 Pro on my laptop for over a year. I installed a 2nd hard drive to it recently and today I installed Windows 8 Pro on the 2nd hard drive. It's been a roller coaster of good & bad luck.
The first install went fine, until I tried to install the Windows 8.1 upgrade from the Windows store, then things went bad and I had to go into Windows 7 and eventually delete the Windows 8 volume and change it from MBR to GPT because of UEFI (no secure boot enabled thankfully). Gawd what a stretch of error messages telling me I can't install Windows 8 on the blank hard drive because it was or wasn't MBR or GPT, or the automagically made partitions weren't in the right order.
After spending over 7 hours twice in a row installing Windows 8, I finally find out that there's no boot option for Windows 7 anymore.
The only clue I have is to use a Windows 7 repair disk and use diskpart.exe and make the Win 7 drive "active" but that's a little foreign to me at this point.