Vim : An Indentation Problem

Hi all

Today a little big problem.
Every time that i copy and past every thing on vim session i have an indentation problem, for example :

1) I want copy this :

Pippo
Pluto
Paperino
Topolino

2) After a copy result is this :

Pippo
         Pluto
                Paperino
                         Topolino                 

Solution ?????
A simple "set paste" can resolve this hateful problem.

Stay tuned.