|Usually with an administrator's account you can take ownership of the disk, unless that was specefically forbidden (it's hard to do that by accident) The owner of a disk does not automatically have permissions on the disk, but he has the permission to change the permissions, so from that point on you could fix the problem.|
Unfortunately my knowledge is limited to experience with Windows XP. Here is what I do, try to do the same in Windows Vista if possible:
-Open "Security" tab in my hard drive's properties
-Click on "Advanced settings"
-Open "Owner" tab
-Under "Choose a new owner" pick your user group "Administrators".
-Check "Replace the owner for subcontainers and objects"
-Click on "Apply"
Then return to the security tab of the properties dialog box. Select "Administrators", check "Total control" under "Allow" and click on "Apply".
Here you go. Hopefully that helped.