AutoCAD Civil 3D :: Zoom Results In Multiple Undo Commands

I am using Civil 3D 2013, Windows 7 x64.

Intellizoom does not seem to work properly on certain drawings, where if I undo... nothing happens. Rather, it tries to undo *each* click of my scroll wheel, without doing anything. This results in dozens and hundreds of undo commands, most of which are totally useless. This of course breaks my undo command, rendering it almost pointless. If I make a change, zoom out and decide that the change is not needed, I cannot easily undo; I have to undo something like 50 "commands" that do nothing, before I get to the "real" undo that I wanted to undo in the first place.

I understand there is the "Combine zoom and pan commands"; this is checked off. It does not seem to do anything. How do I make my undo command useful again? As a keyboard user, I want to use ctrl-z for my undos. I do not want to go to the undo button, pull down the menu, and search trhough the 50 commands to find the correct command to undo to, especially since I never had this problem before in previous versions of Civil 3D.

Some additional information:

1. I can open some other drawings that get the correct undo/zoom behaviour.

2. I can open the drawing I have problems with using a previous version of Civil 3d (2012), and get the correct undo/zoom behaviour.