I managed to change permissions on my own hard drive and locked myself out completely (was my C drive but now set up as a slave). Now the security tab doesn't even show up. Not sure exactly what I set it to that caused the problem. I can only guess that it was a deny setting on Everyone or something???
I've tried takeown.exe from an elevated cmd prompt using the local admin as well as the domain admin among a number of other things that have not worked.