Weird, never-seen-before issue with newly-purchased Dell Inspiron 5420 laptop on Windows 8

Hi everyone, I might have to go to the store again tomorrow to either replace the screen or replace the laptop. But before that, i want to make sure that the issue I'm facing is not something related to the software/driver.

The issue, not apparent all the time, happens whenever any web page (or any window for that matter) with dark/black background is open. For example, if I open www.di.fm, the issue takes place. And the issue is over-saturation of the entire screen.

At first I thought it was some light sensor turning down the brightness of the screen. However, after half a week's use, I'm not sure that it's not related to brightness. It's the saturation of the screen. Whenever a dark page is open, the color begins to over-saturate. The Chrome logo in the task bar becomes extremely saturated. The brightness, too, gets down (not literally, because the brightness slider shows it's still the same).

When I quickly move to another tab or window that has light area, the discoloration of the screen icons/images are immediately visible. It takes roughly 3-4 seconds for the screen to come back to a regular "normal" state.

At first I thought the problem was related to driver or something. I tried installing other drivers/not installing drivers at all, installing different versions of Windows 8 from different discs but at one point of usage, the problem shows up.

Do you know of any issue like this? The problem doesn't take place all the time. But when it does, it's apparent/constant until a restart. I tried logging in to Ubuntu to see if the problem is there, and no, the problem didn't occur. But then again, I didn't use Ubuntu for long enough.

Please help?