My computer has a bay for 2 SSD drives. One is a System Drive (C:), and the other is a Data drive (D:). I also have a 4 terabyte USB external hard drive connected. I swap out different C: drives for different uses ie: one for internet use, a different one for video work, another one for DAW recording etc.. This system worked flawlessly under Windows 7. After installing Windows 10 there is a major problem.
I boot with one of my C: drives. During the course of work I save data to the D: drive or the external drive. If I power down the computer and switch to another C: drive and power up Windows 10 claims to see errors on the D: drive or external drive and proceeds to correct them. Once booted if I look at the D: drive or external drive the data I have just saved minutes earlier is missing. If I try to write to either drive I get an error message saying I do not have permission or the drive is corrupted. If I power down and boot with the original C: drive with which I saved the data files the drives are now un-readable. After many hours of testing I can re-produce the error each and every time I follow the above procedure. The problem seems to be that unlike previous versions of Windows, 10 wants to take possession of drives it sees at boot and does something to them. It seems each bootable C: drive wants to see each data drive in the same state it last saw it. If it does not the problem occurs. I know that my booting from different C: drives is not common but the use of external drives is. The common problem will be if someone saves data to their external drive and then connects the drive to another computer the data loss will occur. There have been mention of this happening already popping up on the web.
The Work-around - I discovered that if I remove the D: SSD drive and disconnect the external drive before booting with a different C: drive, and then power them up again once booted (the D: drive is hot swappable). everything works as expected. The work-around is doable but a pain to remember to do. I hope this helps anyone else experiencing the same problem. Microsoft....please contact me if you want greater detail about the situation.
I really love Windows 10. Microsoft hit a home run with this one. Hope they can get this problem fixed.