I am currently using 3 HDDs in my system. one 320GB, one 1TB and one 2TB. I was using my 320GB HDD as my OS HDD untill early 2015. After that when i got my 2TB HDD I installed my OS (win 7) on that one and formatted the the drive of 320GB which was holding the OS. But recently when I tried to install windows 8.1 on my old 320GB (also the same drive) beside windows 7 as dual boot it gave the following error-
What is the problem here? Can anyone help me with this