The OS is XP-Home. Recently, someone installed a high-speed internet modem and software on this computer, which belongs to a friend. Now, even though he is the only administrator for this computer, he does not have access to his control panel, nor can he run regedit or control. Basically, he is told that the action has been canceled because he lacks permission and should contact his administrator. He cannot run a restore operation. There isn't any obvious way to get to his "users" area to make any changes, since he has no access to his Control Panel.
The usual tricks don't work: Cannot access any Control Panel operations and can not edit registry.