StackOverflow Exception... working with scrollbars

Hi all.
I build a new class for DataGrid control adding an handler to always show
a Vertical ScrollBar in the grid. The code is below.

----------------------------------------------
Public Class MyDataGrid
Inherits DataGrid

Private _imgList As ImageList
Public Event CurrentRowChang ed()
Private oldSelectedRow As Integer = -1

Public Sub New()
AddHandler MyBase.VertScro llBar.VisibleCh anged, AddressOf ShowScrollBars
MyBase.VertScro llBar.Visible = True
End Sub 'New

Private Sub ShowScrollBars( ByVal sender As Object, ByVal e As EventArgs)
If Not MyBase.VertScro llBar.Visible Then
Dim width As Integer = MyBase.VertScro llBar.Width
MyBase.VertScro llBar.Location = New
Point(MyBase.Cl ientRectangle.W idth - width - 2, 2)
MyBase.VertScro llBar.Size = New Size(width,
MyBase.ClientRe ctangle.Height - 4)
MyBase.VertScro llBar.Show() [****]
End If
End Sub

end class
----------------------------------------------------

It runs well: adding new rows to the grid (programmatical ly) updates/resizes
the VScrollBar automatically
showing the VScrollBar since the beginning, even if there are a few rows in
the grid. Adding new rows,
simply updates the VScrollBar (through the Sub above) and all it's OK.

The problem is when I put the datagrid on a TabPage and I click for creating
new rows staying on the
2nd TabPage: this operation causes a StackOverflowEx ception while executing
the line [****].

Uhmm... I don't know absolutely what's the real problem. Can anyone help me?

Many thanks
Francesco