Keyboard of Laptop (NP300E5C-U02IN) acting strange (not working)

Hi

I was working on my assignment for college and suddenly my keyboard stops working I mean it goes in strange mode and suddenly some keys are not working and some keys are working and sometimes those who are working doesn't work but later work. In short , it is not usable at all. Sometimes some letter just keep repeating while I am not using laptop at all. My laptop is brand new and I have hardly used its inbuilt keyboard but I am using external keyboard most of the time and I am making this question from external keyboard. My internal keyboard is not working properly. I have check there is no key pressed and also there was no spill at all on keyboard. It just stopped working middle of no where and I really have no idea why this happened. I am running latest windows 7 came with laptop and my laptop is Samsung NP300E5C U02IN with core i3 second generation processor and 750 hard drive with 4GB ram. If anything else required please ask.

I think some key is pressed permanently , try to clean it with some airblower and see if that fixes the problem.