Hi,
I'm having a problem when I play games using the battery on my Alienware 13. After a few minutes of gaming, the screen will dim to the lowest setting and the usb ports will stop working (my mouse will disconnect). I tried to change the power settings to basically match the plugged in settings in the high performance power profile. I also updated the bios to the latest version. Doesn't matter which game I play, the behavior is the same. I can play a good 20 min or so then the problem comes up.
Few notes: The touchpad works with this problems comes up. The windows slider for screen brightness moves all the way to the dimmest setting when this event is happening.