Hi, my D620 just started having this problem today.

My screen gets all green and static, I think where the static appears depends on the color of things on the screen
I already tried uninstally and reinstalling the video drivers

The only thing that I have done different recently is that yesterday, I started using an Antec notebook cooler. I haven't used any coolers before and it was fine up until today.

Here are some pictures 
http://img521.imageshack.us/img521/9650/68170925vf2.jpg
http://img521.imageshack.us/img521/3002/41496824gr8.jpg
http://img521.imageshack.us/img521/5572/16270343dn6.jpg
http://img210.imageshack.us/img210/1559/33190893wq4.jpg

Here is a direct printscreen from my computer. I'm not sure what you guys will see, but for me its like completely covered with that green statics. Not sure if the printscreen actually captures that green stuff or not.
http://img116.imageshack.us/img116/9342/greendm4.jpg