Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
Check your BIOS settings for Hot Plug/Swap capability for the port it's connected to.
There have also been occurrences of this happening when the Intel Rapid Storage Technology software is installed.
If AHCI/Hot Swap is enabled in your bios, it will come up as a removable drive. Sometimes boards (mostly older ones) will automatically enable hot swap when AHCI is used, with no option to disable it.
After checking the User's Manual for your MoBo, it seems that Hot Plug capability is turned on when AHCI Mode is used, with no option to disable Hot Plugging when in AHCI Mode.