Do you use IncrediBuild? More specifically, do you have the IncrediBuild IDE extension installed? I know that there is a bug with an older version of the IDE IncrediBuild extension that caused problems with moving the current item in the listbox.
Which programming language are you using? This could be C++ or C#
When you have the listbox, how does it look? Is the current item fully selected? Selected just with an outline?