... just to bring this up again
It seems the problem has nothing to do with multiple versions of Illustrator or SolidWorks ...
Versions of Illustrator from CS6 to the current CC are no longer supported.
Translator - Adobe Illustrator
Summary:Error: Adobe illustrator version CS3 or later installation is required to import an Adobe Illustrator file to SolidWorks even with Adobe illustrator CS6 installed.
Comments:Workaround Export the Adobe CS6 file out as a DXF file and then import the .dxf file into SolidWorks
DS SolidWorks does not guarantee that this SPR fix will be available in the indicated future release of the
product since at this time the SPR fix has not completed QA procedures that incorporate all SPR fixes and
enhancements into a new version of our product.