holla was ein source.

Code:
Public Sub StartRadar()
        Me.FormBorderStyle = Windows.Forms.FormBorderStyle.SizableToolWindow
        Me.ControlBox = False
        Me.Height = 260
        Me.Width = 290
        Me.Text = MyAppName             ' neuen Namen in die Titelleiste
        PictureBox2.Left = 0            'Picturebox zum Zeichnen vorbereiten
        PictureBox2.Top = 0
        PictureBox2.Height = 241
        PictureBox2.Width = 286
        PictureBox2.Anchor = 15
        PictureBox2.Visible = True
        PictureBox2.BringToFront()
        Me.Panel3Buttons.BringToFront()
        PictureBox2.BackColor = System.Drawing.Color.White
        NETID("")                           'neuen NetIdentString bauen
        MyRNClass = RadarClass              'Welcher Klasse ich jetzt angehöre
        MyRNSourceClass = ADCClass          'von welcher Klasse mich Daten interessieren
        MyRNSourceID = Convert.ToByte(MyStartValue)
        Disconnect()
        FastConnect()
        'Me.PictureBox2.BackgroundImage = Global.Me.My.Resources.Resources.RadarBack
        'Me.PictureBox2.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Zoom

        Dim TempBitmap As Bitmap
        If Equals(Me.PictureBox2.Image, Nothing) Then
            Me.PictureBox2.Image = New Bitmap(PictureBox2.Width, PictureBox2.Height)
        End If
        Dim LokalDC As Graphics
        LokalDC = Graphics.FromImage(Me.PictureBox2.Image)

        Dim CircleLocalHighSero2 As Integer

        For i As Integer = 1 To PictureBox2.Height Step 40
            CircleLocalHighSero2 = ((PictureBox2.Height / 2) - (i / 2))         'Den Zeichen-Nullpunkt zuweisen
            LokalDC.DrawEllipse(New Drawing.Pen(ColorCircle), CircleLocalHighSero2, CircleLocalHighSero2, i, i)
        Next
        LokalDC.Dispose()

    End SubPublic Sub StartRadar()
        Me.FormBorderStyle = Windows.Forms.FormBorderStyle.SizableToolWindow
        Me.ControlBox = False
        Me.Height = 260
        Me.Width = 290
        Me.Text = MyAppName             ' neuen Namen in die Titelleiste
        PictureBox2.Left = 0            'Picturebox zum Zeichnen vorbereiten
        PictureBox2.Top = 0
        PictureBox2.Height = 241
        PictureBox2.Width = 286
        PictureBox2.Anchor = 15
        PictureBox2.Visible = True
        PictureBox2.BringToFront()
        Me.Panel3Buttons.BringToFront()
        PictureBox2.BackColor = System.Drawing.Color.White
        NETID("")                           'neuen NetIdentString bauen
        MyRNClass = RadarClass              'Welcher Klasse ich jetzt angehöre
        MyRNSourceClass = ADCClass          'von welcher Klasse mich Daten interessieren
        MyRNSourceID = Convert.ToByte(MyStartValue)
        Disconnect()
        FastConnect()
        'Me.PictureBox2.BackgroundImage = Global.Me.My.Resources.Resources.RadarBack
        'Me.PictureBox2.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Zoom

        Dim TempBitmap As Bitmap
        If Equals(Me.PictureBox2.Image, Nothing) Then
            Me.PictureBox2.Image = New Bitmap(PictureBox2.Width, PictureBox2.Height)
        End If
        Dim LokalDC As Graphics
        LokalDC = Graphics.FromImage(Me.PictureBox2.Image)

        Dim CircleLocalHighSero2 As Integer

        For i As Integer = 1 To PictureBox2.Height Step 40
            CircleLocalHighSero2 = ((PictureBox2.Height / 2) - (i / 2))         'Den Zeichen-Nullpunkt zuweisen
            LokalDC.DrawEllipse(New Drawing.Pen(ColorCircle), CircleLocalHighSero2, CircleLocalHighSero2, i, i)
        Next
        LokalDC.Dispose()

    End Sub
so malt man auf dem bitmap und nicht auf dem dc.

todo's für dich wenn das Fenster grösser wird altes bitmap löschen und neues anlegen. wenn die daten kommen dann auf dem bitmap zeichen nicht auf dem dc. source aus misten.

bau mal try blöcke ein damit man auch mit bekomt wenn was schief geht

Gruß