Is there a way to disable the command+up/command+down key combinations?
You can use KeyRemap4MacBook with a private.xml such as this:

&lt;?xml version="1.0"?&gt;
&lt;root&gt;
  &lt;item&gt;
    &lt;name&gt;Disable ⌘↑ and ⌘↓&lt;/name&gt;
    &lt;identifier&gt;DisableCMDUPandCMDDOWN&lt;/identifier&gt;
    &lt;autogen&gt;
      __KeyToKey__
      KeyCode::CURSOR_UP, VK_COMMAND | ModifierFlag::NONE,
      KeyCode::VK_NONE
    &lt;/autogen&gt;
    &lt;autogen&gt;
      __KeyToKey__
      KeyCode::CURSOR_DOWN, VK_COMMAND | ModifierFlag::NONE,
      KeyCode::VK_NONE
    &lt;/autogen&gt;
  &lt;/item&gt;
&lt;/root&gt;


Just CURSOR_UP, VK_COMMAND without | ModifierFlag::NONE would also disable for example option-command-up.