Search for "z fighting". There's a lot of information on this. You can a face slightly above the edges. Due to the size of the model space and your graphics card, the edges underneath are showing through sometimes.

OH MY GOD! Now i get this error when i use JPP plugin General Problem: cannot compute the transformation & then SketchUp BugSplat. how I can recover the original file "Win32api.so"? I think that is the cause of this problem ... Help please.. thx!