Basicly, when you install a program on your XP Pro OS, it usually ask you if you want to allow other users to access this program or just you.
If you choose Just me then the ability to access this program from other users account is denied.
If you want to change it you can open you Control Panle, go to Administrative Tools and open Service Components.
In the tree select computers -> my computer -> DCOM and there select your program.
Right click on it and select properties, and on security teb you can select access control, and defined it as you wish
Monday Night, It's Online Casino