You should be able to reassign the shortcut in the Customize Keyboard dialog
box. Click the Office button, and then click Word Options. In the Customize
category, click the Customize button. Under "Categories," choose "All
Commands." In the "Commands" box, select EditUndo. Choose "normal.dotm" for
"Save changes in." Place the insertion point in the "Press new shortcut key"
box and press Ctrl+Z. Click Assign. Close the dialog box. When/if you are
prompted to save the template, choose to do so.
