From when I bought it up until yesterday, my laptop would dim the screen automatically if you let it sit for long enough, and then if you hit a key or moved the mouse, the brightness would jump back to what you had it at. I enjoy that behavior. It works well.
Then I booted it up today, and found that now it will dim the screen automatically if you let it sit for long enough, but it doesn't restore the screen brightness. I have to do that manually, every single time, and it's getting really old really fast.
It's an Alienware M17 running Windows 7 64-bit, in case that helps.
EDIT: After a bit of testing, I've found out that it only does this on the Power Saver profile, while on AC power. Other power profiles work fine, as does Power Saver on the battery. But I can't find anything in the control panel that looks like it would affect this.