My pointer moves to the top left icon on screen after a while

I have a Dell Inspiron 15R with windows 7 32-bit installed on it . Whenever I open my desktop and select any random icon, after some time (around 10 sec) the pointer will move on the top left icon on screen and it will freeze there . I try moving it with arrow keys and it won't move . My touch-pad works just fine and I am not pressing any key accidentally. I also tried using a usb mouse but it was still happening .Whenever I am typing the pointer would move to the beginning of the line and I would have to type all over again . If I am using Powerpoint or Microsoft word after a while it the first page of the word or powerpoint file will open . Even in Pdf files if I am reading it will just shift to the first page of the file .