Studio Studio XPS 16 Strange Problem

Hi Everyone,

I have a month old Dell Studio XPS 16 which up until yesterday has been a wonderful laptop. The issue has to do with my AC adapter and the display. When I boot the laptop without the AC Adapter plugged in there is absolutly no issue at all. Once booted if I plug in the AC adapter the screen immediatly darkens and there are a number of shaded triangles across the bottom of the screen. The screen is not too dark to where I cannot see the desktop, but definatly enough to be aggrivating especially with the triangles at the bottom of the screen. The powersupply must be pluged in to the outlet to cause this, and I did try another powersupply and it does the same thing. When I unplug the ac adapter the screen will not return to normal until the computer is rebooted again without being plugged in. I plugged in an external moniter and this problem is not noticable on it. Another thing I find strange is that without being plugged in the screen is especially bright, almost as though it were plugged in. If anybody has any idea what could be causing this please let me know, I really appreicat any input provided.