Help with a viao pcg-581L keyboard problem

Hello,
I have been laid off and to occupy my time I fix up old laptops to donate and on this older laptop I put in 7 ultimate and it worked great. Then I did windows update for the first time and now some of the keys on the keyboard ie hitting the u key types a 4 instead, aaarrgghh, will type a different letter than what it is supposed to. The touchpad and mouse functions work fine. Any help would be greatly appreciated
thanks in advance!!