Hi Lee,

You need to modiify the KeyActionMappings of the editor for the column. Something like this: 

        private void ultraGrid1_InitializeLayout(object sender, Infragistics.Win.UltraWinGrid.InitializeLayoutEventArgs e)
        {
            UltraGridLayout layout = e.Layout;
            UltraGridBand rootBand = layout.Bands[0];
            UltraGridOverride ov = layout.Override;

            rootBand.Columns["Int32 1"].Style = Infragistics.Win.UltraWinGrid.ColumnStyle.IntegerNonNegative;           
            EditorWithMask editorWithMask = (EditorWithMask)rootBand.Columns["Int32 1"].Editor;

            for (int i = editorWithMask.KeyActionMappings.Count - 1; i >= 0; i--)
            {
                KeyActionMappingBase kam = editorWithMask.KeyActionMappings[i];
                MaskedEditAction actionCode = (MaskedEditAction)kam.ActionCode;
                if (actionCode == MaskedEditAction.UpKeyAction ||
                    actionCode == MaskedEditAction.DownKeyAction)
                {
                    editorWithMask.KeyActionMappings.Remove(kam);
                }
            }           
        }

Note that the editors are shared by all of the columns in the grid with the same Style. So if you get the editor from the column's Editor property like I am doing here, this will affect all of the columns in the grid that are using that editor, which is probably what you want in a case like this. If not, you would need to declare a new EditorWithMask and do the same thing, then assign it to the column.