Using OpenSCAD I created a 3mm thick flat plate and placed two vertical cylinders on it of 5mm diameter and 50mm height, separated by about 40mm (.scad and .stl files attached).

I sliced this using Slic3r (yeah I know, I know!), then previewed the gcode using Repetier Host in "single layer view" (.gcode attached).

As I scroll up the layers I can see the little circles that make up my cylinders gradually get further and further apart. Is this the slicer putting in some automatic compensation for the shrinkage of the plastic as it cools, or is the visualisation of the layers simply wrong in Repetier Host?

When I print the object the cylinders are vertical!

Gawd, I just realised what this is. Please ignore me - I'm even too embarrassed to reveal what the "problem" was now...