Inspiron Laptop getting pink and purple lines on screen

Hi,  I am new to forums.  I have had MANY Dell computers including several desktops and I am now on my third laptop.  My previous laptop had the processor die after only a couple of years.  I replaced that laptop with a 14 inch Inspiron which I love.  Lately, something strange is happening to it.  For the most part, it works fine and my display is fine.  Every couple of days, for no apparent reason, my entire screen will end up pink and purple lines that go vertically sometimes and horizontally sometimes.  There is no option other than to reboot.  When I reboot, all is fine again and I can use the laptop like normal.  I never know when this thing with the lines is going to happy nor do I have any idea why it is happening.  I did this diagnostic check thing on the Dell site and everything passed.  I went to the drivers area and downloaded some of the 41 recommended downloads.  The problem is that now I just don't trust the laptop.  I fear taking it on trips for fear it will crap out when I am away from home.  The laptop was purchased in April of 2012 so it isn't even a year old.  I didn't save the box or packaging material and so I don't even know how I could mail it back. 

My daughter has a 17 inch Dell laptop and she has had this same situation happen with her system although she has only had it happen 3 times in total whereas I seem to have it happen far more frequently.

 I hope that someone out there has an idea of what can be wrong or what we are doing wrong that is causing this problem.

Thank you in advance,

Muffinski