Especially useful if you are in places such  as China, Korea or Japan… if you see this error message

The pack name is invalid

KB article KB973561 (You cannot convert a basic disk to a dynamic disk when the computer name contains double-byte characters)

  1. Swipe in from the right edge of the screen, and then tap Search. Or, if you are using a mouse, point to the lower-right corner of the screen, and then click Search.
  2. Tap or click Settings, and then type rename this computer in the search box.
  3. Tap or click the displayed Rename this computer icon.
  4. On the Computer Name tab, tap or click Change.
  5. Type a new name under Computer name, and then tap or click OK.

also instructions for how to do this with Windows 7 or Windows Vista can be found at the KB article

Get more help and support for Windows 8

Rob