Flickering pixels and bluish-screen.

Hi,

I have been having a problem with my Dell Inspiron n5110 laptop. It was working completely fine until today.

At first, all of a sudden while using the laptop in morning, the screen started giving weird green flickering pixels/micro-dots on various parts of the screen (not whole screen). I shut it down instantly and after a while started it back. The issue remained and then in a few minutes they went away. It was working fine again. I shut it down after using it around an hour or so. In evening, i started using it again and same problem arrived while watching a video. Parts of the screen flickered with green dots..and they seemed to form patterns with animations (videos or even buttons on windows that light upon moving cursor on them). Then a few bands (thick horizontal stripes) started moving across the screen from bottom to up. And now (within half an hour) the whole screen is greenish-blue with weird pixels stagnant on whole screen. Attached is a screenshot of the screen. Kindly let me know what is this problem and the solution for it.
I googled for this problem and found out that it might be an issue with graphic card heating. But i have taken care of this laptop more than usual. I use a Cooler Master Dual fan cooler (with special cool aluminium body)  every time I use the laptop. Since this is my working laptop, I have never played games on this laptop that demand high-end graphics or anything such. I have a separate desktop machine with high-end graphics card and processor for gaming/graphics purpose. When i purchased the laptop, it used to heat up a lot especially below left corner of the keyboard (left of touchpad). I immediately purchased the cooler and even then the heat-up problem persisted. I found out on the internet that this specific model has body-design issues and heats up a lot. Since then, just to be cautious, I never left the use of cooler. 

I will be very thankful for your support. Looking anxiously forward for assistance.