- Download this little partition editor from Symantec. N.B Had to use a shortened URL as Posterous doesn't like FTP links.
- Run the exe and select the 3rd partition as shown (If the partition is currently visible, it will be showing '07' like the other partitions)
Click in the first column and choose Set Type and select option '17', Hidden IFS (NTFS, HPFS) as I've done.
- Save Changes, exit and reboot