Overlapping or self intersecting facets

I am having trouble printing the last part for my filamant spool for my prusa mendel.

http://www.thingiverse.com/thing:30742

when I slice the spool_axle_holder.stl with slic3r 0.9.3 I get an error
"The model has overlapping or self intercecting facets......."

When I start to print the second layer looks like it tries todo a massive overhang that fails.

I have the same problem with overhang-test.stl, bridgetestpart.stl and perimeter-wt.stl from the calibration wiki.

Thanks.

Run it through Netfabb, there are a lot of parts on thingiverse that are "bad", skeinforge seems to manage to slice some of them despite the errors, but the current version of Slic3r is supposed to be able to slice anything Netfabb blesses as manifold.

Thanks. I ran all my files through netfabb. Sic3r still complains about the interceting facets but they show up in pronterface. I will have to print tonight and see it I can finish the calibration wiki..

But are 3 of the stls in the calibration wiki dodgy or is something else going on here. Should I be making the move to skeinforge?