Comment 49 for bug 397892

I cleaned out my users .gnome* .gconf* etc.... and my screensaver/power-saving started working again, however, if I go to screensaver preferences and make a change, it stops working until the next logout/login.

I can not be sure that the fresh .gnome* .gconf* made a difference, or if that coincided with a change in the package.
I am also not 100% sure that mucking with the screensaver preferences breaks it, but others should give it a try.