Several years ago I built a desktop computer for my friend. I installed Windows 7 Ultimate on this, in the 64 bit version, and I followed user Kari's tutorial for placing User data and ProgramData on a separate physical hard drive. The system drive for Windows 7 was on drive C:, and I had a separate physical drive, D:, exclusively for her User data (that is, all the user accounts on the system) and ProgramData.
This worked very well for her.
Then last year, my friend upgraded her system from Windows 7 Ultimate to Windows 10. I'm not sure what flavor of Windows 10 she has -- perhaps it is Windows 10 Pro. She did this on her own. I believe it is still a 64 bit operating system, but I never checked. The upgrade process went very well. She still had her User data on the separate hard drive, D:\.
A few days ago, my friend expressed concern that she might lose her user data. Drive D:\ was a "Samsung 840 Pro" SSD device, the 512 Gb size. I thought I would clone this drive to a brand new SSD drive, a "Samsung 850 Pro" SSD, which is also 512 Gb.
Last night, I asked my friend to shut down her computer. Then I removed the Samsung 840 (drive D:\ with all the user data) and I cloned this to the new Samsung 850 Pro SSD. To do the cloning action I used the Gnu ddrescue product.
The cloning action took only about 40 minutes, and after it was completed, I took the Samsung 850 device to her computer, connected it to exactly the same SATA cable and power connectors as the Samsung 840 was connected to, and turned on the system power.
Windows 10's splash screen showed up, then the monitor went blank. It stayed blank for the next 10 minutes. There was no indication of what was happening. (I did theorize that chkdsk might be running, but when it does, one would expect a command prompt window to show up.) At that point I powered off the computer. I was wondering if I had improperly connected the power and data cables to the Samsung drive. I checked these, and they seemed okay.
Then I powered on the computer again.
The system went into an "automatic repair" loop which I am unable to resolve such that the system will boot up. "automatic repair" will start, then a screen presents itself that says "diagnosing your PC", then finally a panel shows up claiming that my system has to be restarted. It offers a button to click to restart the system. But the "automatic repair" loop starts after every restart.
Substituting the old Samsung 840 Pro SSD also results in the same "automatic repair" loop.
The advanced options menu in this utility offers a command prompt, and I have run `chkdsk f: /f /r /x' and `chkdsk d: /f /r /x' on both the system drive (it shows up as drive f:\ and the user data drive (as drive d:\, with no problems found on either hard drive. Attempts to restore a system restore point dated May 31, 2016 have failed. I cannot run in Safe Mode. I cannot run diskmgmt (disk management) to check on the drive lettering. "Automatic repair" gives no clue as to why the automatic repair process started. I'm not sure if I can start the registry editor from the command prompt.
My best guess is that the new drive might not have the drive letter D:. I'm not sure how to check on that.
Thanks for any advice that can be offered.