Setting File Permissions to an external hdd in XP. Big Problem...

I wanted to restrict access of my computer's external hdd to other user's of my computer and I followed this guide. Only problem is that I selected 'Full Control' of the Deny option for 'everyone' and it won't even let me access my hdd (I have admin privileges). I even tried logging onto the admin account in safe mode and it still won't let me. When I try to re-edit the settings for the security tab under the properties of the hdd it just tells me the following:

http://i209.photobucket.com/albums/b...ermissions.png

Any ideas?

It looks like this might help me but I do not know how to access the GPO. If I had to would re-installing Windows fix this?

lol Ok, I already fixed the problem. I just had to go into my D drive's properties then 'Security' then 'Advanced' and set permission there.