Re: Backlight gets reseted with VDPAU
I have Dell Vostro 3700 (GeForce GT 330M), kernel 2.6.36 and nvidia-drivers 260.19.29 and have the same problem. I have found out that when the compositing in KDE4 is switched on/off, "something" (probably nvidia-driver) resets the brightness level of the display to the last value set by Fn keys, ignoring the current level.
I assume the switch of compositing is a trigger - I can see this happen also when e.g. going to fullscreen video playback or switching to VT (but only when compositing is enabled).