Message with policy

Archived from groups: microsoft.public.windowsxp.security_admin (More info?)

Hi,

I have a serious problem with the group policy,

When I try to go to change the power time I have an error message, I have a
portable with XP Professional SP1

What I do , I go to:

1. Display
2. Screen Saver
3. Power
4. Settings for portable / Laptop power scheme
I try to change the <Turn Off monitor> from After 5 mins. To After 1 hour

When I click to Apply:

I have this message:
the name of the message dialog: Power policy manager unable to et active
policy
The mesage: Not all priviliges referenced are assigned to the caller

Notice that: I am the adiministrator of the machine

Any help please

Thanks in advance