XPS M1330 - screen flickering when unplugged

This laptop has had a long history of problems , i first ordered it with the Nvidia Graphic card which crashed  and had to be replaced 4 times until I decided to replace the entire mainboard for one with Integrated Intel Graphics to avoid the problems. Therefore I have no graphic card anymore, and so far had no troubles.

About  a week ago I had a partition crash, so I had to reinstall everything, before that I had no problems with my monitor, but now every time I unplug the AC adapter, the computer starts flickering.

This time when I reinstalled I used Genius Drivers to find the correct drivers for Win7 since Dell doesnt post them in the website.Driver Genius said I needed an ATI driver which seemed werid to me but I installed it anyway, I figured out that the installer would say something like: there are no ATI devices found. But it didnt. So The first thing I did after a week of flickering (when unplugged) was to uninstall everything from ATI, but the problem is consistent.

Can anyone give me a hand? could it be the driver??? or a missing driver?? If so where are the correct ones?

Thanks in advance for any help!