Screen Flashes/Flickers multiple colors??

Hello:                                                                                OS: Windows 8 Home Premium 64 bit : Dell Inspiron 7720 : NVIDIA GPU

Last night i was getting ready to shut down my laptop when suddenly the screen began to flicker different colors such as magenta, yellow, cyan etc. It wouldn't stop until I did a forced shut down.

Then I waited a few moments and restarted. It came back on okay and so then I ran every diagnostic tool I could think of to run. I ran the Dell diagnostics and Norton and everything Passed. Except It says that my Hard Drive is 26% fragmented but then when I hit Analyze and then tell it to fix the problem it will start to run a bit and then it stops and just returns to saying 26% ...

So, just now I turned my laptop on for the day and it did the same thing! The screen began to flicker the various colors. I have checked and the computer states that the video drivers are all up to date and working properly. I suppose, maybe I ought to go directly to the the maker's website for the updated drivers ... ?? Maybe there is a more up to date driver?? One can hope.

Also, I am aware there is an update to Windows 8 to 8.1 but I usually wait a little to do updates to make sure there aren't worse then what they are supposed to be fixing. Do you think that could be my problem?

Although I bought this computer back in April/May ... I haven't actually used it much at all. It's quite close to the way it was when it was delivered to my door w/the exception of having downloaded Adobe Creative Cloud, Photoshop, Illustrator, Indesign, Inkscape and Gimp.

Please, if anyone has any idea what could be causing the flickering please let me know. I greatly appreciate your time and help.

Oh, also ... one would think that Dell would install a fan that can keep this latop cool while the GPU is in moderate/high use but that doesn't seem to be the case. The computer easily overheats and I do use a fan underneath it at all times.

Thank you again! Hope everyone is having a good holiday season and for those who aren't my thoughts and prayers are with you. <3 Thanks for your time!