Problem with laptop keyboard

[mindblogg]

My laptop keypad is behaving strangely for some reason. When I type s for example it displays 'st'. or when I type 'i' it displays '.i' What could be the probelm? Is it something with my keypad or motherboard.
I am currently using a USB keyboard .

 

[jdiddy]

That happed to my dads m505 before. I resat the keyboard and it worked fine afterwards.