I have been having an unsual problem with my keyboard.
I am using Windows XP. When I try to type some keys like underscore (_), some
numbers like 7,9; the shortcut keys in MS word and even on internet gets
acrivated. For example, “H” appreads over home, “N” appreads over Inser, “P”
appreas over “Page Layout” and so. To get rid of it, I have to click on “Windows”
shortkey on the key. But again same thing appreas as I type the above keys.
This is so troublesome specially when I have to work with Excel and have to
type lots of numbers.

I tried to search a lot on internet to fix this problem
but could not manage to fix it as of now. 
Can someone suggest what might be the problem and how to fix it?

For your reference, I am also including the snapshot of
the shortcuts getting activated automatically.

Thanks.