You have to start command prompt as an Administrator (On Windows 7 that means right clicking the cmd and selecting Run as Administrator) and use the diskpart utility.
WARNING: Be careful to select the right drive or else your day won’t have a happy end because if you select the wrong drive you will lose all your data on this drive!
Instead of formatting the partition with FAT32, you can also use NTFS (like WUDT does), but then you need an extra step to make the drive bootable:
Bootsect.exe /nt60 X:
“X:” is the drive letter of your USB stick. Bootsect.exe can be found on the Windows 7 DVD in the boot folder. However, I can’t really recommend using NTFS. Some USB stick, at least, appeared to be slower with NTFS.
- Start command prompt as Administrator and type diskpart
- type list disk
- type select disk and number of your USB disk ( like select disk 1 )
- type clean
- type create partition primary
- type select partition 1
- type active
- type format quick fs=fat32
- type assign
- type exit to exit the diskpart utility
- type exit to close command prompt
Unable to copy files using windows 7 usb/dvd download tool – Microsoft Community.