surface normal

Hi,
I have an STL model (or a VRML model) that its surface normals are not
consistent. That is, some of the normals point out and some of them
point in.
Is there a way in SolidWorks (or elsewhere) to resolve this problem and
make all the normals point out?
When I load the STL file into SolidWorks, it gives me a warning that
says: "A facet normal problem was found with one of the facets in the
file. Please check the STL file." (it's a large model and it has
several facets, so I can't possibly go through it and manually fix the
normal direction.)
When I load the VRML file (of the same model) into SolidWorks, I select
'Import as a solid body' from the load options. But the result is the
same.
Any idea?
Thanks,
Babak ( babak_taati at yahoo dot com )