Keyboard working improperly!!!

A bad contact would either type or not type, it would not type something else. I have to disagree with Solutions58, while I might check the ribbon cable that attaches to the motherboard, I would suspect it far more likely that it's related to the software. Probably OS settings or something with Macros attached to that specific device.

Download a live OS CD or DVD, something easy and small like UBUNTU, OpenSuse, tiny Linux, etc. (It won't wipe your PC) Just use it to test if the problem goes away when you boot to another system on CD/DVD. If it does, it is totally a software problem. Try spyware scanners, virus scanners, remove any macro software, reinstall your OS, whatever...you know where to look.

Otherwise, at least you know it is a hardware problem and can replace the keyboard with the knowledge your fixing the problem and not just changing a setting as a product of adding new hardware that may only fix the problem temporarily.

1. this issue is due to the contact in the keyboard have become worn and the keyboard is in need of replacement.
2. the keyboard connector cable has become loose to the mother board.
3.This will need a service tech to check.