I have Windows XP on a Dell Dimension 3000 Desktop and I use Internet Exporer as my browser. Anytime I press "0" (zero) on the number pad, not on the top row of numbers, it opens a new window in Explorer. I tried a different keyboard to see if it was mechanical, but it did the same thing. My keyboard is a standard issue Dell. Language setting is US. I don't know what else it might be.