Inspiron N5110 Keys producing multiple incorrect characters

Hi, My laptop (Inspiron N5110) has developed a fault where pressing any keyboard key produces 2 or 3 incorrect characters. Such as I press "A" and I get "qya" or similar. I have done a full factory restore but the problem persists and I can not enter a username to set up Windows 7 because it is impossible to type. I suspect that in my short absence from the room a few nights ago, one of my kids "may" have spilled a drink on the table where the laptop was being used - but they won't come right out and admit it ! However there was a slightly sticky patch on the underside of the laptop. Is this the likely cause ? The laptop is working perfectly apart from this... Any ideas ? Many thanks in advance.