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Switching Hard Disk Causes Boot Error
I've upgraded one of my machines to Windows 10. I put in a new SSD and left the old Windows 7 drive alone, just unplugged. I wanted to leave it intact in case I decided to downgrade. I should mention that I did an upgrade install of Windows 10 by installing Win 7 to the SSD first.
The problem is this: Today I realized that I needed to use something briefly from the Windows 7 drive which did not work on Windows 10 yet (replacement program arrives on Monday). I unplugged the Win 10 drive and plugged in the Win 7 drive and rebooted.
It would not boot up. It got halfway into the colored fly-in, gave a brief BSOD which I couldn't read, and then rebooted. It did this multiple times before I ran Startup Repair. Startup Repair didn't help at all, but it did tell me that there was a driver error. I tried System Restore and safe mode and neither worked. Safe mode just stalls at "ClassPNP.sys" and then BSODs and reboots.
Nothing has changed in this machine hardware wise, so I don't get why there is now a driver error. It's not like the motherboard would remember the Windows 10 configuration. Going back to Windows 10 works fine.
Any ideas, anyone? I'm at a loss.