I tried the files your sent to me, and FBX Converter seems to have a bug because the OBJ file contains a few numbers suffixed by [font=courier new]#IND00[/font] or [font=courier new]#QNAN0[/font], like [font=courier new]1.#IND00[/font]. If you remove all these suffixes (with a simple text editor), you'll be able to import the OBJ file.
The imported file will be all gray, but this is another issue I can't help you about, since the MTL file that should contain colors and textures description is empty!