Offline (The disk is offline because it has a signature collision with another disk that is online)

Issue

I replaced a drive that had Windows Vista Business 32-bit so that I could do a clean install of Windows 7 and still keep Vista just in case. After Windows 7 was fully installed, I hooked up the original hard drive using an Apricorn DriveWire USB Hard Drive Adapter. The Apricorn DriveWire was detected by Windows 7 but the hard drive did not show up in Windows Explorer. I then installed the original hard drive as a secondary SATA drive. Still no joy. I then checked Disk Management, and low and behold, the drive was listed but was “offline” with the following message:

Offline (The disk is offline because it has a signature collision with another disk that is online)

Solution

I right-clicked on the drive in Disk Management and choose online. I was then able to access the drive without any problems or conflicts.