请教：点击DataGridView列标题进行排序时出现的问题

所有的列都是用代码动态的生成，查询出来的结果完全正确的在DataGridView里显示（数据源绑定），但是当DataGridView纵向上有滚动条时，把滚动条拖到最右边，然后点击最右边的那一列标题进行排序，点击两次排序后就会出现如下的错误信息：未将对象引用设置到对象的实例。
Source: System.Windows.Forms
   在 System.Windows.Forms.DataGridView.ComputeVisibleColumns()
   在 System.Windows.Forms.DataGridView.LayoutScrollBars()
   在 System.Windows.Forms.DataGridView.ComputeLayout()
   在 System.Windows.Forms.DataGridView.PerformLayoutPrivate(Boolean useRowShortcut, Boolean computeVisibleRows, Boolean invalidInAdjustFillingColumns, Boolean repositionEditingControl)
   在 System.Windows.Forms.DataGridView.OnColumnWidthChanged(DataGridViewColumnEventArgs e)
   在 System.Windows.Forms.DataGridView.OnBandThicknessChanged(DataGridViewBand dataGridViewBand)
   在 System.Windows.Forms.DataGridView.AutoResizeColumnInternal(Int32 columnIndex, DataGridViewAutoSizeColumnCriteriaInternal autoSizeColumnCriteriaInternal, Boolean fixedHeight)
   在 System.Windows.Forms.DataGridView.AutoResizeAllVisibleColumnsInternal(DataGridViewAutoSizeColumnCriteriaInternal autoSizeColumnCriteriaFilter, Boolean fixedHeight)
   在 System.Windows.Forms.DataGridView.OnAddedRow_PostNotification(Int32 rowIndex)
   在 System.Windows.Forms.DataGridViewRowCollection.OnCollectionChanged_PostNotification(CollectionChangeAction cca, Int32 rowIndex, Int32 rowCount, DataGridViewRow dataGridViewRow, Boolean changeIsDeletion, Boolean changeIsInsertion, Boolean recreateNewRow, Point newCurrentCell)
   在 System.Windows.Forms.DataGridViewRowCollection.OnCollectionChanged(CollectionChangeEventArgs e, Int32 rowIndex, Int32 rowCount)
   在 System.Windows.Forms.DataGridViewRowCollection.AddInternal(DataGridViewRow dataGridViewRow)
   在 System.Windows.Forms.DataGridView.RefreshRows(Boolean scrollIntoView)
   在 System.Windows.Forms.DataGridView.DataGridViewDataConnection.ProcessListChanged(ListChangedEventArgs e)
   在 System.Windows.Forms.DataGridView.DataGridViewDataConnection.currencyManager_ListChanged(Object sender, ListChangedEventArgs e)
   在 System.Windows.Forms.CurrencyManager.OnListChanged(ListChangedEventArgs e)
   在 System.Windows.Forms.CurrencyManager.List_ListChanged(Object sender, ListChangedEventArgs e)
   在 System.Data.DataView.OnListChanged(ListChangedEventArgs e)
   在 System.Data.DataView.UpdateIndex(Boolean force, Boolean fireEvent)
   在 System.Data.DataView.UpdateIndex(Boolean force)
   在 System.Data.DataView.SetIndex2(String newSort, DataViewRowState newRowStates, DataExpression newRowFilter, Boolean fireEvent)
   在 System.Data.DataView.SetIndex(String newSort, DataViewRowState newRowStates, DataExpression newRowFilter)
   在 System.Data.DataView.set_Sort(String value)
   在 System.Data.DataView.System.ComponentModel.IBindingList.ApplySort(PropertyDescriptor property, ListSortDirection direction)
   在 System.Windows.Forms.DataGridView.DataGridViewDataConnection.Sort(DataGridViewColumn dataGridViewColumn, ListSortDirection direction)
   在 System.Windows.Forms.DataGridView.SortInternal(IComparer comparer, DataGridViewColumn dataGridViewColumn, ListSortDirection direction)
   在 System.Windows.Forms.DataGridView.Sort(DataGridViewColumn dataGridViewColumn, ListSortDirection direction)
   在 System.Windows.Forms.DataGridView.OnColumnHeaderMouseClick(DataGridViewCellMouseEventArgs e)
   在 System.Windows.Forms.DataGridView.OnMouseClick(MouseEventArgs e)
   在 System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   在 System.Windows.Forms.Control.WndProc(Message& m)
   在 System.Windows.Forms.DataGridView.WndProc(Message& m)
   在 System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   在 System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   在 System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   在 System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   在 System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
   在 System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   在 System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   在 System.Windows.Forms.Application.Run(Form mainForm)
   在 Resoft.PS.View.SysStart.Main() 位置 E:\project\统战部（地方版）\03源代码\PersonalitySystem(v1.2)\PersonalitySystem\View\SysStart.cs:行号 144