I experience a crash if I use the column chooser to to hide a column that is used in a summary definition that has DisplayArea="InGroupByrecords" and the XamDataGrid is using GroupBySummaryDisplayMode="SummaryCellsAlwaysBelowDescription".  Is very easy to reproduce and happens 100% of the time.  Just use settings below

---FieldLayoutSettings

<igDP:XamDataGrid.FieldLayoutSettings>
    <igDP:FieldLayoutSettings HeaderPlacementInGroupBy="OnTopOnly" HeaderPrefixAreaDisplayMode="FieldChooserButton" GroupBySummaryDisplayMode="SummaryCellsAlwaysBelowDescription"/>
</igDP:XamDataGrid.FieldLayoutSettings>

--SummaryDefinition

<igDP:SummaryDefinition Key="mySumm" SourceFieldName="Price" DisplayArea="InGroupByRecords" Position="Left" Calculator="Count">
</igDP:SummaryDefinition>

--Field

<igDP:Field Name="Price"></igDP:Field>

all you have to do is startup the project and open the Field Chooser and try and hide the Price field.  You will get this

Exception: Index was outside the bounds of the array.

Stack Trace:

   at Infragistics.Windows.DataPresenter.VirtualizingDataRecordCellPanel.ReuseCellElements(IList`1 newVirtFields, IList`1 newNonVirtFields)

   at Infragistics.Windows.DataPresenter.VirtualizingDataRecordCellPanel.VerifyFieldLists()

   at Infragistics.Windows.DataPresenter.VirtualizingDataRecordCellPanel.MeasureOverride(Size availableSize)

   at System.Windows.FrameworkElement.MeasureCore(Size availableSize)

   at System.Windows.UIElement.Measure(Size availableSize)

   at System.Windows.ContextLayoutManager.UpdateLayout()

   at Infragistics.Windows.DataPresenter.GridUtilities.ProcessAsyncInvalidationsImpl()

   at Infragistics.Windows.DataPresenter.GridUtilities.ProcessAsyncInvalidations()

my current work around is to not allow hiding of this column