/// <summary>
        /// 在最后一笔添加新行 
        /// </summary>
        public void AddNewRow()
        {   
             dataGridView1.Rows.Add();

             int i = dataGridView1.Rows.Count - 1;

             dataGridView1.CurrentCell = dataGridView1[0, i]; // 强制显示该行

             dataGridView1[0, i].Selected = true;   //光标移至该行


        }

        /// <summary>
        /// 删除最后一笔记录，或者选定的记录
        /// </summary>
        public void DeleteRow()
        {
            if (dataGridView1.CurrentRow == null)
                return;
            dataGridView1.Rows.Remove(dataGridView1.CurrentRow);
        }

        /// <summary>
        /// 在选定的记录上面插入一笔记录
        /// </summary>
        public void InsertRow()
        {
            if (dataGridView1.SelectedRows.Count >= 1)
            {
                int iIndex = dataGridView1.SelectedRows[0].Index;
                dataGridView1.Rows.Insert(iIndex, 1);
            }
        }

------解决方案--------------------

是你cells超出范围不是rows

------解决方案--------------------
C# code

  while (this.dataGridView1.Rows.Count != 0)
  {
    dataGridView1.Rows.Clear();
  }