I know it seems strange but apparently the problem remains when autocad is closed, even if it's possibile that the program is running some way actually.

But the point is that it's really hard to use the system with this trouble and i had to renounce to use autocad for mac.

I think that it's quite absurd that it is unsolveble: it's not an hardware problem but happens only on a few number of computers. Apple didn't help me at all, and more, the kind macbooks are just a few and mine it's one the most common...it seems magic, not computer science! I'm not blaming anyone of course, the only hope it's that we will have some news from autodesk about that or that someone more experienced with softwares will find some solution!

Thank you anyway maxim!

Andrea.