Go online and go to "Options" menu Scroll down to "Global" Scroll down to "unit Management" and that's where the Space bar is hotkey'ed. Simply click the little "X" next to the Bind hotkey and the space bar shouldn't do anything.
you have to be more specific... unbinding the space *bar. would cause it to do nothing. why do you press the space bar in your game? is it a alert? is it to write a text? we don't really know. the 'function' of the space bar is set in your game options. there isn't anything really in the editor per-say that would change a key press outside of a hot key. but - i assume that's not the problem.