To reproduce:

Create a self reference RadGridView and add enough columns so that a horizontal scrollbar appears. Scroll the horizontal scrollbar to the right and close the form. You will see an exception.

Workaround:

Create a custom row element in the CreateRow event:

void radGridView1_CreateRow(object sender, Telerik.WinControls.UI.GridViewCreateRowEventArgs e)
{
    if (e.RowInfo is GridViewHierarchyRowInfo || e.RowInfo is GridViewDataRowInfo)
    {
        e.RowElement = new MyDataRowElement();
    }
}

public class MyLayout : SelfReferenceCellLayout
{
    public MyLayout(GridRowElement rowElement) : base(rowElement) { }

    public override void DetachCellElements()
    {
        if (this.StackLayoutElement != null)
        {
            base.DetachCellElements();
        }
    }
}

public class MyDataRowElement : GridDataRowElement
{
    private MyLayout cellReferenceLayout;

    public override void Detach()
    {
        base.Detach();

        if (this.cellReferenceLayout != null)
        {
            this.cellReferenceLayout.DetachCellElements();
        }
    }

    protected override void DisposeManagedResources()
    {
        if (this.cellReferenceLayout != null)
        {
            this.cellReferenceLayout.Dispose();
        }

        base.DisposeManagedResources();
    }

    public override SelfReferenceCellLayout SelfReferenceLayout
    {
        get
        {
            if (this.RowInfo is GridViewHierarchyRowInfo)
            {
                if (this.ViewTemplate != null &&
                    this.ViewTemplate.IsSelfReference &&
                    this.cellReferenceLayout == null)
                {
                    this.cellReferenceLayout = new MyLayout(this);
                }

                return this.cellReferenceLayout;
            }

            return null;
        }
    }

    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(GridDataRowElement);
        }
    }
}