I hooked another internal hard drive up to my computer. I already had two drives installed one SSD that has Windows 7 installed and one 1TB standard drive. I use the SD drive to install programs and keep files. After I installed the 3rd drive it changed my SD drive letter to letter E: and gave 3rd drive letter D: which is what the SD drive was before. Now when trying to do anything on the computer it pops up and says C:\whatever the specified path doesn't exist. When trying to do a diskpart from CMD I get the same error: C:\Windows\System32\diskpart.exe the specified program doesn't exist Even though the programs is there. When I try and download a program it does the samething. I don't have a disk I can use to change the storage drive back to letter D: I would have never thought this would happen since Windows is installed on letter C: and that is still there.