problem in blender 2.59.0 can't do anything in edit mode

With a mesh selected in object mode I tabbed into edit mode only to find I could select vertices and edges and faces but could not grab or scale or rotate anything. After over an hour of aggravation I found that because I entered zero on one of the axis in the scale transform in the properties shelf in the 3D viewport I caused the problem. Entering a value other than zero fixed the problem. I entered a zero because I added a circle mesh which is a flat object and when I typed in my scale values for all my axis I entered zero for the axis with no dimension thinking it wouldn’t matter. Is this a bug?