Ok i fixed it :
First of all i turned off all my AA settings on nHancer and in FH2 options.
Then i also deleted the cache folder in the :
documents/battlefield2/mods/bf2/cache
When i restarted the game, shader optimization has been made and the bug disappeared.
After that i restarted nHancer on 32x by forcing the AA.
Now all work perfectly and i'm still playing with AA in hight value !!!