Hi David, 

There's nothing in the grid that would prevent the cell from changing twice. It must be something in your code that is doing that. 

The code you have here is a bit strange and I think what might be happening is that you are causing recursion here. 

Calling e.Cell.Row.Update() is not really a good idea. And there's certainly no reason to call it twice, as you are doing here. I suspect you are probably doing this because if you don't, the Value property will return the original value of the cell and not the new value. 

What happens because the Value property of the cell reads from the data source, and the DataSource has not been updated at the time when CellChange fires. That's because for many cells, updating the Value of the data source every time the cell changes would cause problems. For example, if you have a DateTime cell and the user types into that cell, whatever they type would not be a valid value for the cell until they type in enough to make a complete date. So CellChange fires on every keystroke. 

For CheckBox cells, of course, this is not a problem. But by forcing the entire row to be committed, you might inadvertently cause an exception because some other cell in the same row might have a pending change that isn't valid, yet. 

I suspect that what might be happening here is that you are committing the value of the cell and then you are SETTING the value of the cell, which may be causing CellChange to fire again recursively, and after that I'm not sure what happens, but this probably isn't the best way to achieve what you want here. 

A better way to handle this and get the current value of the cell as it appears to the user on-screen is to use the Text property of the cell instead of the Value.

Dim goodsDelivered As Boolean = Boolean.Parse(e.Cell.Text)

It looks like what you want to do is prevent the user from checking the Checkbox until the Delivery Date field is filled in. So rather than setting the value on the cell, which could cause recursion, you would be better off setting the Value on the cell's editor. And that way, there's no need to call Update on the Row. 

 Private Sub UltraGrid1_CellChange(sender As Object, e As CellEventArgs) Handles UltraGrid1.CellChange
     If e.Cell.Column.Key = "Goods_Delivered" Then
          Dim goodsDelivered As Boolean = Boolean.Parse(e.Cell.Text)
          If goodsDelivered = True Then
               If IsDBNull(e.Cell.Row.Cells("Final_Delivery").Value) Then
                    Dim checkEditor As CheckEditor = e.Cell.EditorResolved
                    checkEditor.Value = False
               End If
          End If
     End If
 End Sub