Thank you again guy for your advices.
Actually I can’t suggest to upgrade the software 'cause I’m an “external” collaborator, and even if it is the simplest solution, it is out of my possibilities.
By my side I’ve found a simple workaround. I simply open the .3ds on the Rhino in my office 'cause it works, and then I re-saved in .3ds. It works.
I’d like to ask you in this case if it possible to automate the process in rhino, using these actions:
-Open one by one all .3ds file into a folder (the folrder path is fixed, it doesn’t change)
-Re-save in .3ds format overwriting the old one.
Is it complex? Or can I do even if I’m not a pro Rhino user?
Thank you very much again.