I thought I'd pass this along for anyone else that hadn't figured this out: 1) Open a command prompt and type "diskpart" and hit enter. 2) Type "list volume" and hit enter. 3) Among the listed volumes, you'll see the 100mb system partition; in my case it is volume 1. 4) Type "select volume _", (inserting the appropriate volume number). 5) Just to the right of the numbered volumes, you'll see the corresponding drive letter listed. Note the drive letter, then type: "remove letter _", inserting the observed drive letter. Hit enter. That's it.