Oops, you're right! I fixed my code above. Alternatively you could create a Sub that enables the buttons correctly...
Code:
    Public Sub FixButtons()
        ' First make all of the buttons Enabled...
        btnToStart.Enabled = True
        btnPrevious.Enabled = True
        btnToEnd.Enabled = True
        btnNext.Enabled = True

        ' Now disable those buttons for the fringe cases...
        Dim index As Integer = Me.TblStudentsBindingSource.Position()
        If index = Me.TblStudentsBindingSource.Count - 1 Then
            btnToEnd.Enabled = False
            btnNext.Enabled = False
        ElseIf index  = 0 Then
            btnToStart.Enabled = False
            btnPrevious.Enabled = False
        End If
    End Sub
And then just call that Sub after each "movement". For example:
Code:
    Private Sub btnToStart_Click(sender As Object, e As EventArgs) Handles btnToStart.Click
        Me.TblStudentsBindingSource.MoveFirst() 'Moves to the First Record
        FixButtons()
    End Sub