If you installed the game as an administrator then it should have been installed as being accessible to all users, however XP is rather inconsistant with this process and sometimes it doesn't work with many programs. One possble method is to change your user account to admin, install the game in that account, then change it back to limited user. It is almost certain, if the game was installed on the admin account, that a limited user won't have access to the admin accounts files and folders, this is basic computer security, don't allow restricted users access to the files and folders of the admin users.