XPS 17 going to black screen at random using usb devices or normal computer use.

Sometimes when I'm using a USB Stick, memory card, external hard drive or using a program that causes the screen to go black. I have to use the mouse to make it come back and as soon as I pull out the devise the screen will go black again causing me to have to use the mouse. Until I do a reboot it will do this everytime.

Also if I'm using a program that has User Account Control it will cause the screen to go black, then I have to move the mouse, then it will go black again because of user Account and black again unlike normally how User Account Control makes the screen go black.

As I'm typing this now the screen went dark at random twice causing me to have to move the mouse! I'm don't even have a USB devise connected. It'll fix it with a reboot but will come back a few days later. I've reformatted the XPS a month or so ago because of this and it's back again. I still have a warranty with Dell so what should I do? What could be the cause of this?

I have the i7-2720qm and the NVIDIA GeForce GT 555M 3GB graphics with Optimus.

This is really starting to frustrate me. I've had this laptop less then 2 years and I've already had to replace the palm rest, the hard drive, had a huge hassle with the fans running alot and now this.

It's getting to the point where instead of happening every few weeks it's happening every few days.