We are finding that sometimes when we sort by group by columns using a custom GroupByComparer we are getting a stack overflow exception.  

I am attaching a sample project to illustrate this problem with grid version 12.1.20121.2008.  To reliably produce the exception, just group by Issuer, then by Parent Company. Sort by Parent Company and observe the exception.  Notice that the test program adds less than 2000 rows to the grid and it is still possible to get the exception.  Note that removing the following line:

tbl.Rows.Add((i / 10).ToString(), i.ToString(), (i / 100).ToString(), 

1000000 - i);

allows the grid to be sorted successfully even if we add thousands more rows. I believe that the underlying sorting algorithm used in the grid may be failing for even modestly sized data sets if they are in nearly worst-case sorting order.  Is there a way to avoid this exception?