Yes, Erel you are right.. but, uninstalls/installs and other tries have did not solve the issue
Finally, I solved the problem it in the "hard" way.. let's say: hammer and chisel
I've copied the whole folder c:\Windows\Microsoft.NET from the correct computer to the wrong computer.. and yes, everything is Ok now!
I don't know that specific problem was inside .net, but never mind.. and this solution has been better than formatting the computer
Thank you very very much to all of you that have been helping to me.. I appreciate very very much the solidarity from this community
Best regards for all you