Lubuntu TF2 Shortcut key disable

I when using the Lubuntu 14.04 desktop and playing TF2. If I press CTRL + Spacebar TF2 minimize. The key combo doesn't do anything in other programs. I do not have this problem on other desktops like Unity, Gnome, Xfce. And I have tried them all. I have also checked lubuntu-rc.xml and have found nothing in it to indicate that CTRL + Spacebar would do anything. I can not find anything to disable it. Let alone that it even exists. If anyone could point me in the right direction to disable this. I would be very much welcomed.