When you press "del" help window will open

Hi to everyone!

I have this problem very long time ago untill now.

When I press "del" key a help window will open, also some characters have accompanied by other letters. for example when I press "s" it gives me "s1" others are "w" = w7, and the worst is when I press "2" the system will force to shutdown.

I have used diff. anti virus like mcaffee, norton and pccillin with updated dat files. I also update my system to the latest service pack after I reformat it to make sure I got a very fresh and secured system, but it doesn't protect me.

My system:
OS: Win XP
Service Pack 2
Pentium IV 2.4g

Any help will be highly appreciated! please! it really ruin my time. and I'm afraid that someday all of my files will turned to .exe or unusable.

Please help.