Cannot execute boolean operation with imported SVG I imported some SVG objects, extracted them and converted them to a mesh. When I tried to perform a boolean difference operation between them, I saw the error message "Cannot execute boolean operation". When I looked in the console, I saw these errors:

uncontained hole loop does not share vertices with any face loop!
CSG failed, exception /build/buildd/blender-2.72.b+dfsg0/extern/carve/lib/triangulator.cpp:898  "didn't manage to link up hole!"
CSG failed, exception /build/buildd/blender-2.72.b+dfsg0/extern/carve/lib/triangulator.cpp:898  "didn't manage to link up hole!"
CSG failed, exception /build/buildd/blender-2.72.b+dfsg0/extern/carve/include/carve/csg_triangulator.hpp:330  unpaired.find((*i).first.first) == unpaired.end()


Here is a link to the file that I'm trying to use. I'm trying to subtract the 'QR' object from the 'BG' object. Is there something wrong with the meshes resulting from the import/extract step? What's going on here?
You could try and deal with this in another way.  

I selected an upwards facing face and used shift+g->normals to select all the other faces that are facing upwards and deleted them.

Now if you select edges and press f, the faces can be filled in quickly enough.  

By doing this, you can build up the large box without having to use the boolean modifier.