Pressing up arrow shuts down computer

[szlats]

I recently reformatted my master hard drive and re-installed Window XP Pro.  At the same time I installed Linux OS on my slave drive (Ubuntu Feisty Fawn).  Since doing this whenever I press the up arrow button the computer shuts down.  It will do this if I boot to either Windows or Linux OS.  How can I change the function of the up arrow to move the cursor and not shut down my machine?

[contrex]

Do you mean it just goes off - POW - the very same moment you press the up arrow, or that it goes into a normal shutdown?

Is it a laptop or desktop? If a laptop, I would suspect a loose connection or faulty component right under that part of the keyboard. If a desktop, is it a USB or PS/2 keyboard?

You posted this on CNET Forums too.

On there, Supermaster wrote,

Your keyboard has probably become defective. Check with some other keyboard whether the problem persists or not.

That is good advice. Try another keyboard.

Although this is very strange. I do not see how the same keypress could shut down the PC in both Windows and Linux.