How do you cancel Clipping Border?

2.53?

2.49?

d2

A simple search for clipping border in the wiki brings up the result
http://wiki.blender.org/index.php/Doc:Manual/3D_interaction/Navigating/3D_View#View_Clipping_Border

2.49 - in camera view (numpad 0), press shift B to select a border - to remove, toggle the “border” button in the Render Tab or the scene buttons (F10)

2.53 - Shift B will allow you to choose the border - to remove, uncheck the Border toggle in the “Dimension tab” of the render buttons

Or just do a new border with SHIFT+B which enconpasses the full render region.