编辑已在C＃中绑定和更新列的DataGridView

I have a DataGridView where the DataSource is a BindingList. Most of the columns are updated -- via various timers which call PropertyChanged("...") for the bound columns. One column -- the problematic one -- is a DataGridViewComboBoxColumn -- where the user selects an item from the list of Items.I have a DataGridView where the DataSource is a