ArcMap add-in (vb.net) datagridview will crash map when right click on the title part

Question

I find the problem accidentally. In my ArcMap add-in, there is a search function which allows the user to search the geodb based on the value of a field. It works fine but today when I right click the title in the datagridview casually, the ArcMap crashed. After that I simulate the scenario several times, every time ArcMap crashes.

My code is listed bellow:

Sql = "SELECT ITEM_NO AS 'ITEM NO', ITEM_CATEGORY_NO AS 'ITEM CATEGORY NO', ARRIVAL_DATE AS 'ARRIVAL DATE' FROM testDB WHERE ITEM_NO = '" + item_No + "'"

Try
        adapter = New SqlDataAdapter(Sql, connObj)
        adapter.Fill(ds)
        connObj.Close()
        DataGridView1.DataSource = ds.Tables(0)
        Catch ex As Exception
           MsgBox(ex.ToString)
End Try

The result is:

Once I right click the part in the red frame, the map will crash.

Can anyone please tell me what's wrong with my code?