In the photo, the checkbox for 'Automatically mount this partition' is behind the Change button
Thank Paul but are you referring to my photo or Mike's because I do not see that option on the HDTool?
Mark a partition and click on "change", and you will see a tick for "Automount", remove that and the partitions will not be attempted mounted by the OS, and will not appear as NDOS on Workbench.
Out of curiosity - why do you have them in the first place?
EDIT: OK, I read this thread some more - something is clearly very weird with your system. Do you have more hard drives attached?