Commented Issue: Custom Pivot table : editing a Σ field crashes Excel [14798]

See attached test project and see attached Excel file.

Clicking on "Records Not Processed" and "Value Field Settings" crashes Excel ???

The Pivot table is created using this code:
```
public class SimplePivotTable
{
private readonly IEnumerable<string> groupByColumns;
private readonly Dictionary<string, string> summaryColumns;

/// <summary>
/// Constructor
/// </summary>
public SimplePivotTable(IEnumerable<string> groupByColumns, Dictionary<string, string> summaryColumns)
{
this.groupByColumns = groupByColumns;
this.summaryColumns = summaryColumns;
}

/// <summary>
/// Call-back handler that builds simple PivatTable in Excel
/// http://stackoverflow.com/questions/11650080/epplus-pivot-tables-charts
/// </summary>
public void CreatePivotTable(ExcelPackage pkg, string pivotSheetName, ExcelRange pivotDataRange)
{
var wsPivot = pkg.Workbook.Worksheets.Add(pivotSheetName);

var pivotTable = wsPivot.PivotTables.Add(wsPivot.Cells["A1"], pivotDataRange, pivotSheetName);
pivotTable.ShowHeaders = true;
pivotTable.UseAutoFormatting = true;
pivotTable.ApplyWidthHeightFormats = true;
pivotTable.ShowDrill = true;
pivotTable.ShowCalcMember = true;
pivotTable.FirstHeaderRow = 1; // first row has headers
pivotTable.FirstDataCol = 1; // first col of data
pivotTable.FirstDataRow = 2; // first row of data

foreach (string row in groupByColumns)
{
var field = pivotTable.Fields[row];
field.Sort = eSortType.Ascending;
pivotTable.RowFields.Add(field);
}

foreach (var column in summaryColumns)
{
var field = pivotTable.Fields[column.Key];
var result = pivotTable.DataFields.Add(field);
result.Name = column.Value;
result.Function = DataFieldFunctions.Sum;
}

pivotTable.DataOnRows = false;
}
}
```

Please advice.
Comments: I'm seeing the same problem on Excel 2007 (12.0.6665.5003) SP2 MSO(12.0.6662.5000).