How can a prevent my backspace button on my keyboard from turning into a web ';go back'; button?

When typing out an answer here on Yahoo Answers or in other form boxes, when I hit the backspace button to a few times fast to erase a word, it instead acts like the internet explorer ';go back'; button and changes to previous web pages. I then lose what I have typed in the form. How can I turn off the feature that suddenly turns the backspace button into a web ';go back'; shortcut button?How can a prevent my backspace button on my keyboard from turning into a web ';go back'; button?
If your cursor is in the textarea (the box you type in) it's a backspace button. If not it's a ';back 1 page'; button. That's how browsers are written.