Form.Show() wont work after closed

[At--o]

Using VB Express 2010 in windows XP Pro 64.

A ListBox shows the project forms names.
On ListBox_DoubleClick

    For Each F As Form In xFormCollection
    If F.Name = ListBox.SelectedItem.ToString Then
    Try
    F.Show()
    Catch ex As Exception
    MsgBox(ex.Message)
     
    End Try
     
    End If
    Next

Works fine the first time but after closing the form opened by the DC, if I try to open it again, throws an exception "Cannot access a disposed object".

Since I can still access any other form not previously showed I guess that the closing changes a status that allowed the form to be .Show, there is
no F.Load , F.Activate after the exception doesn't seem to do anything. What should I do?