In PowerPoint, holding down Shift when resizing an object such as a line should restrict the movement of the end point to be either vertical or horizontal. This is useful for resizing horizontal or vertical lines that you wish to stay horizontal and vertical.
In PowerPoint 2010 this appears to not always work. When I re-size a line while holding Shift the movement is still restricted in direction, but the object snaps to some absurd length (i.e. hundreds of inches).
This behavior is not consistent (i.e. sometimes the object re-sizes as expected but sometimes it snaps to infinity), but the odd behavior appears unique to PowerPoint 2010.
Why is this happening and how do I prevent it?