And it's a mess to fix. BEFORE you try anything be sure all your files you can't lose are on backups. Only then should you the too plentiful fixes from the web. My view is to clone the old to the new drive instead and move the ssd to the boot drive's connection as well.
But I will never tell anyone there is a solid fix or exit other than this. Go ahead and try https://neosmart.net/EasyRE/ but so many will not buy it.
CPU: Intel I5-2400
Mobo: Asus P8H67-M Pro
RAM: 16G DDR3 1333
HDs: Fujistsu 256Gb SSD, 2 x Seagate 2Tb, 7,200; Seagae 1Tb
OS: Windows 10 Home & Windows 7 Home
I had a bunch of trouble with crashes and a corrupted C drive recently, so I bought an SSD and made that my new C drive. Initially, I set it up as dual boot (can't remember why, but it worked), with the original (corrupted) C drive as D (with Win 10) and the new C drive (with Win 7) on the SSD.
I wanted to get rid of the original boot drive (now D) to reformat that disc for extra storage. But I wasn't sure if it would cause any problems. So I tried disconnecting the drive (by pulling out the SATA cable) and rebooting, and I got this message: <Reboot and select proper boot device or insert boot media in selected boot device and press key.>
Will I get stuck with this message if I reformat the D drive (i.e. the former C drive)? Or is physically disconnecting that (D - the original OS) hard drive not the same thing as reformatting it (since, in both cases, what you're doing is eliminating the old boot drive)?