I have experienced this quite a few times, but never really understood why. Before I have not seen it (I think) on drawings that I have made my self, but on drawings imported from architect dwg files and such that perhaps was not in correct scale.
But here the drawing scale is 100, but what I measure and what I measure is not the same, a factor 25 something wrong.
How I made this drawing: I had a similar drawing on A3 landscape in scale 1:200 - but I wanted to "zoom in" and have the drawing in 1:100. So I made a new drawing, with A3 portrait, scale 1:100 and copied parts of the first drawing to this new drawing.
How to fix this??
[Blockierte Grafik: http://i744.photobucket.com/albums/xx81/Thorvald73/Building%20construction/Measurementsproblem.jpg]