Comment 5 for bug 555709

Additional info.

I logged in using the "xterm" session and this did not happen, so I started looking at the various default startup applications. When I disabled the gnome-power-management daemon the screen brightness stayed bright, as expected. So, it seems the gnome power manager is erroneously adjusting the brightness down at login. I haven't tried disabling it for the "gdm" profile to keep it from dimming the login screen.