I'm running Windows Server 2008 standard on my network file server, I have two hard drives one for general files and the other for accounts info. I want to limit access to just the general drive and grant access to the accounts drive to certain network users.
I don't understand why it doesn't work in your case. I always used that method in a couple of cases and never failed.
This would fail if the parent folder has full permisions, so the folder you are restricting also inherits the parents permisions, so check the parent folders and if so just remove completely permisions on parents and just set them on individual drives or folders.
Best practise is never to let complete drive acces, just individual folders to selected users or user groups.