How To Install Windows 7 From a bootable USB Drive Next we'll use the bootsect utility that comes on the Windows 7 disk to make the flash. Files copied successfully. However, we were unable to run bootsect to make the USB device bootable. If you need assistance with bootsect. You can easily fix Unable to run bootsect to make the USB device bootable Error in Windows by getting the tool “Windows 7 USB DVD. Tonight I had a DVD with Windows 7 that used to work, but it wasn't BOOTSECT /NT where the drive letter is the USB drive. Hi, also trying to create a bootable USB device to install Windows 7 and getting the error that bootsect isn't working even if you put it in the.