Bug in Framework 1.1 SP1 for DataColumn Expressions in a DataGrid

Along with Framework 1.1 SP1, Microsoft introduced a bug for a
DataColumn Expression:

I have two tables in a dataset and these tables have a parent-child
relationship. The parent table has an expression in a column that sums
the values from a column in child table:
ds.Tables[0].Columns["Msg"].Expression = "Sum(Child(Messages).Flg)";

Both tables are hooked up to a datagrid.

If I go in the child table and try to edit that column, datagrid
navigates back to the parent table without the user intervention. If I
want to go back to the child table, I get the error "Object reference
not set to an instance of an object."

The error can be reproduced only on .Net Framework 1.1 SP1. I could
not reproduce it on Framework 1.1 prior to SP1, I have also tested on
Framework 1.0 (SP3) and no error.