The computer I use for video editing has the C drive for the operating system and programs and he E drive, an internal hard disk, for data. I regularly use the Windows 7 backup tool to create a disk image so I can restore the C drive in case of a crash. All of a sudden the backup tool has decided that the E drive is a system disk and insists on including it in the image backup. Given the many hundreds of GB of video on E, there is no room on my backup device to create an image of both C and E.
How can I remove the "system" designation from E?