For some unknown reason, his keyboard seems to have started to work perfectly well now. However, I wonder, whether it was virus OR spyware OR adware OR anything else that could've been responsible for that. But then again, it's hard to imagine such problem causing from virus, spyware or adware.
In the mean time, it was rather surprising for me to know he DID NOT have any virus removal software, at all, in this system. He's however, now installed the virus removal system.
Oh well, All's Well That's Ends Well .............. as Shakespeare once said
Thanks to every single one, who took their time in helping me out & is greatly appreciated.