When ArmA 2 CTD's on you with error message of: Error Too Many Objects In Grid 1023,1023 - it means that you have some objects placed outside of the map range.
What does that mean is when you look at Visitor 3 map view you see objects there, but you cannot see the objects that are placed outside the map view. Usually they get placed there by copy pasting a (large) set of objects or by using external tools to create the objects.
In some cases if you have not copy pasted or used external tools and that you are sure there is no objects outside the visual Visitor 3 map view, then you can scroll around the edges of the map view and move/delete all objects that are really close to it.
You can debug the object coordinate ranges by exporting all objects either by using the Visitor 3 own script (slow) or with Mikero's DePew tool and then scanning it with text editor to find coordinates beyond your map's range.
Rule of thumb is; know where your objects at! :)