Sounds like it is trying to use a drive letter that is already in use.
Right Click on “My Computer” and left click “Manage” to open up Computer Management.
Select “Disk Management” on the left to populate the area on the right with all of your disk drive information.
Look for something labeled “Disk #” that has 16GB of space and probably no drive letter. Right click and select “Change Drive Letter or Paths…” and choose {P:} or any other letter you aren’t using already.