How Can I Disable Keyboard Entry?

I have a cancel button on a form that I want the user to be able to fire only with a mouse click. If it has focus, pressing the space bar will fire it. I don't know about other keys. This is usually not a problem but when an exceptionally large file is processed, the display may turn off and if the user presses the space bar to turn it on the cancel is fired. I could set the focus on another command button but the same kind of thing could interrupt the program. So, how can I prevent this from happening? I have considered putting in a text box that is not visible and sending focus there but am hesitant to do that.