VB.net Cannot access a disposed object on form close : I am trying to make some code for a game that has a grid and a tick counter but  the grid just tries to fill the window instead of stopping and does not display the tick counter. The Error that keeps coming up is "A first chance exception of type 'System.ObjectDisposedException' occurred in System.Windows.Forms.dll". I have no idea what this means and i don't know how to fix it please help.
Heres the code:

    Public Class Form1
        Dim G As Graphics
        Dim BBG As Graphics
        Dim BB As Bitmap
        Dim r As Rectangle

        Dim tSec As Integer = TimeOfDay.Second
        Dim tTicks As Integer = 0
        Dim MaxTicks As Integer = 0

        Dim IsRunning As Boolean = True

        Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            Me.Show()
            Me.Focus()

            G = Me.CreateGraphics
            BB = New Bitmap(Me.Width, Me.Height)

            StartGameLoop()
        End Sub

        Private Sub DrawGraphics()
            For X = 0 To 19
                For Y = 0 To 14
                    r = New Rectangle(X * 32, Y * 32, 32, 32)

                    G.FillRectangle(Brushes.BurlyWood, r)
                    G.DrawRectangle(Pens.Black, r)
                Next
            Next
            G.DrawString("Ticks: " & tTicks & vbCrLf & _
                        "TPS: " & MaxTicks, Me.Font, Brushes.Black, 650, 0)

            G = Graphics.FromImage(BB)

            BBG = Me.CreateGraphics
            BBG.DrawImage(BB, 0, 0, Me.Width, Me.Height)

            G.Clear(Color.Wheat)
        End Sub

        Private Sub StartGameLoop()
            Do While IsRunning = True
                Application.DoEvents()



                DrawGraphics()

                TickCounter()
            Loop
        End Sub

        Private Sub TickCounter()
            If tSec = TimeOfDay.Second And IsRunning = True Then
                tTicks = tTicks + 1
            Else
                MaxTicks = tTicks
                tTicks = 0
                tSec = TimeOfDay.Second
            End If
        End Sub
    End Class