Screen brightness won't adjust

Can you change it in the Power Configuration screen?

I am having the same issue. I can no longer adjust the screen brightness on my XPS 1647.  I believe the problem started after installing windows 7 64bit service pack 1. The problem persists after uninstalling SP1.  

I cannot adjust via Fn UP/DOWN or via the power config screen. Nor does the display auto dim when on battery power. 

any one else having the issue? 

I suggest checking to see if you have Quickset installed on the system.  It may be downloaded from the following link.

I would also check to see in the bios if the Funtion key is enabled or the multimedia key.  Hold the up or down arrow while pressing the multimedia key and see if that helps.

TB

Fn key is working fine, the transparent graphic with the sun pops up and the arrow slides back and forth, but screen brightness remains the same. 

Where you able to bring up Quickset? Just to make sure that it is installed.   If the screen is showing at full brightness it could possibly be a problem with the inverter or LCD screen.  If this is something that has happened recently I suggest running system restore just to make sure that it isn't a Windows issue.  The following link provides instructions to run system restore.

TB

I have the latest Quickset installed, the thing that pops up when I change the brightness shows me what it should be, but the brightness doesn't change at all.

You should disable your video driver and enable it again. That should do the trick.

Thanks for the assist.  Solved the issue by going in Device Manager and updating drivers for the display adapter (Intel(R) HD Graphics)