Both laptop keyboard and virtual keyboard will not type certain letters

My son has a Dell Inspiron running Windows Vista. His computer was fine and he made no changes to it whatsoever. He came to me very upset claiming that his keyboard was not working properly.

I took a look at it and sure enough, it will not type the following letters:c,h,l,t, ***U,v. Since his password contained the letter "L," once he logged out he was no longer able to log back in.

He asked me to reinstall his operating system. I have done so, except now I'm on the screen where it asks me to type a username and password - and guess what? It still won't type those letters! I even tried the virtual Dell Inspiron Keyboard - it will not type those letters using it either. However, when you press the "U" key (whether on the keyboard or the virutal keyboard) a window pops up titled: Ease of Access, and it gives me the option of hearing text onscreen, making items larger, etc.

I cannot even begin to imagine how to fix this. Please, if any of you know what to do, help me please??