Need help with drive permissions

[EJ_42]

I have an external HD which I use on two computers. I modified the
permissions on a directory and set \Users to deny read. Now I can't
change it back, even when I log in as admin. Can anything be done to
fix this?
I tried a system restore and the restore process says it cannot restore
settings on the external HD because it's been detached.

 

[EJ_42]

I tracked down how to do this by forcing an ownership change.

In XP Home, boot in safe mode and log in with an admin account.

1. Right-click the folder that you want to take ownership of, and then
click Properties.
2. Click the Security tab, and then click OK on the Security message
(if one appears).
3. Click Advanced, and then click the Owner tab.
4. In the Name list, click your user name, or click Administrator if
you are logged in as Administrator, or click the Administrators group.
If you want to take ownership of the contents of that folder, select
the Replace owner on subcontainers and objects check box.
5. Click OK, and then click Yes when you receive the following message:

You do not have permission to read the contents of directory folder
name. Do you want to replace the directory permissions with permissions
granting you Full Control?

All permissions will be replaced if you press Yes.
Note folder name is the name of the folder that you want to take
ownership of.
6. Click OK, and then reapply the permissions and security settings
that you want for the folder and its contents.