Color management Problem - XP pro

Hi all.

I would like to change the gamma settings for my monitor using adobe gamma.
Strangely, the adobe gamma's gamma slider doesn't affect the gamma settings
of my monitor at all (as if it doesn't do anything!), and also none of the
color profiles in the color management settings of my monitor have any
affect on the way my monitor displays pictures.

Monitor: LG E700B
Graphic: ATI Radeon 7000
Win: XP pro SP2


I also tried uninstalling and reinstalling both monitor and the graphic card
drivers. These did not work at all.

Thanks for any help.