First: let me thank forum owners for letting me participate.
Second: I apologize for my english
and Third, my problem...

I'm a new user of Civil 3D version 2013. This problem I'm facing does not happen in Civil 3D 2012.
The fact is that when I execute Corridor properties and try to use zoom icons to select assemblies or modify Start or end stations the zoom icons don't work, they don't get high lighted and so I have to scroll and zoom using my mouse or go to View menue and zoom using the displayed commands. I wonder if it is lack of RAM (I have 4 Gb) or some setting I have not set.

I would be very gratefull to receive an explanation of what is happening and how to fix this problem.