Inspiron 14 3420 - freezes and displays random horizontal lines pattern

I bought Inspiron 14 3420 Laptop in December 2012. I am facing some display problems on this laptop, it freezes and displays horizontal lines patterns (exactly like: http://www.youtube.com/watch?v=zOjTK4ic1E8) and it happens randomly and not always.
It happened few months before and then automatically got fixed, I thought this could have happened due to some applications installation. But now its happening very frequently, I don't know what is causing this.
I tried changing and updating display drivers for both integrated Intel's graphics card and Nvidia display card, but problem is still there.
I tried googling this problem and found that this could be Nvidia graphics card problem, so I disabled this card from Device Manager, but this didn't fix the problem.
Can you please help me fixing this problem