So I updated my drivers recently and the Fallout 3 profile in the "Manage 3D settings/profiles" tab in the control panel won't 'stick' anymore. I have to untick the "show programs you have installed" option. When I set the Ambient Occlusion on I see no difference. It's making me wonder if none of the applied settings are sticking at all. I'm also worried other games will be affected too!

Have you tried removing then re-adding FO3 in the profiles?