this.dataGridView1.MultiSelect = false;
int IndiceRiga = 0;
for (IndiceRiga=0; IndiceRiga < this.dataGridView1.Rows.Count; IndiceRiga++)
{
     if ((long)this.dataGridView1.Rows[IndiceRiga].Cells["ID"].Value == lng_ID)
     {
          this.dataGridView1.Rows[IndiceRiga].Cells["Nome"].Selected = true;
          break;
     }
}
this.dataGridView1.MultiSelect = true;
this.dataGridView1.Rows[IndiceRiga].Selected = true;
this.dataGridView1.FirstDisplayedCell = this.dataGridView1.Rows[IndiceRiga].Cells["NomeFileOriginale"];