dear Eddie
Just to keep you posted
Updated again Premiere and tried some of the tips you suggested: nothing doing
Finally I verified the file system (which actually doesn’t work wery well);
-too many Program versions were saved
-the same prevew and rendering folders and files were repeated up to five times, at various levels, and the System was unhable to mantain control on rendering.
So I deleted all those prevew and rendering folders and files and copied in one Progect version all the related files of the other versions and then cancelled them.
Now (I say it in a low voice)the problem seems to be solved
Thanks for your help
egisca