Board Thread:Questions and Answers/@comment-24520194-20140208070236/@comment-5165836-20140208201840

Well... typically, when people have problems installing, it's due to administrator accounts. If you aren't already, try logging in as an administrator and installing it that way.

All Vocaloid 3 packages come with the tiny editor, which would be the "vocaloid voice editor" you speak of. Studio one is for instruments and the extra full voice editor Miku and other Crypton Vocaloid 3 products come with called "Piapro studio". Even if you plan to use the full editor and ignore the tiny one, you still need to install the tiny one because the full "Piapro studio" editor reads the voice from the tiny editor.

Also... you do realize that what you have there isn't just Miku English, it's her V3 package that comes with both the English and Japanese versions, right?