Hole is filled on some layer (linux-x86_64-1-0-0-RC3)

Hello,

I try to print Pen_Arm_Top.stl of [www.thingiverse.com]. Unfortunately the triangular hole gets filled every few layers with three layers of material. Had a similar issue when printing a gear cube with RC1 earlier, but at that time it was only one layer which could easily be cut out.

Slic3r's build in viewer shows the model completely correct with the hole. However, after slicing the triangular hole is filled (see attachment).

Setting are as follows:
; generated by Slic3r 1.0.0RC3 on 2014-03-09 at 13:30:20

; layer_height = 0.2
; perimeters = 3
; top_solid_layers = 4
; bottom_solid_layers = 4
; fill_density = 0.20
; perimeter_speed = 30
; infill_speed = 60
; travel_speed = 130
; nozzle_diameter = 0.4
; filament_diameter = 1.75
; extrusion_multiplier = 0.95
; perimeters extrusion width = 0.40mm
; infill extrusion width = 0.67mm
; solid infill extrusion width = 0.67mm
; top infill extrusion width = 0.67mm
; first layer extrusion width = 0.60mm

Found a workaround: Rotating the object by 90 degree around z-axis resolves the problem.