Dell Laptop Vostro sleeps as soon as power chord is attached or detached.

Hi All, 

I have a issue with the Vostro 3558. As soon as I connect the power supply to the laptop, the laptop goes to sleep mode and takes me to the log in screen. Same happens when I disconnect the power from the laptop. This happens sometimes and not always. 

Recently I had a motherboard failure and Dell replaced it for me. This issue was there before and even now with the new motherboard. So I am thinking this could be a driver / software problem.

Let me know what you think. Thanks in advance.