Hi Ws,
the AppleMNT.sys is the driver for enableing read access to your OSX partition while in Windows.
You can disable this driver by doing the following while in Windows:
1. Click Start, then My Computer.
2. Double-click on the BOOTCAMP (C:) drive At the These files are hidden screen, click on Show the contents of this folder.
3. Double-click on the Windows folder. At the These files are hidden screen, click on Show the contents of this folder.
4. Double-click on the System 32 folder. At the These files are hidden screen, click on Show the contents of this folder.
5. Double-click on the drivers folder.
6. Locate the file AppleMNT (it is a .sys file) and rename it to something like AppleMNT_keep.
7. Click Start, then click on Shut Down.
8. Click Restart to restart Windows.
Since the OSX partition might still be shown in the 'Disk Management Console' you might wanna restrict access to this console as well.
Regards
Stefan