I am trying to import photos from aperture using the lightroom functionalities. Some of those photos are systematically rejected (i.e. some of the .jpg, which do not look different from the others).
The import text file just states that "possible reasons include unsupported files".
I cannot loose all those pictures just because I transfer to lightroom...any solution?
Use your copy of Aperture to EXPORT them as JPEGs. Not to import from Lr via the plugin. Once you've exported a test of one of the offending JPEGs, see if Lr will add it, or if other software can view it.
Check out Aperture Exporter; it makes all that much easier.