[2005] Printpreview errors when calling from mdi parent

Here is the elusive error! The error only kicks in sometimes and when it does, the printpreview does not work again without restarting the application.

PrintPreviewDialog1.ShowDialog()
ArgumentException was unhandled
Parameter is not valid.

I’m not sure what the error is talking about because it works 50% of the time. I thought at first it might have been an issue with the amount of time it took for the graphics drawing which is why I added plenty of pauses inbetween each statement. I can actually comment out all of the code within the print event and it will still not reach it and crash.

Also if my coding looks horrendous (which I’m sure it might seeing as though printing is all self taught) then any hints would be great too.

Below are the printpreview menu click event from the mdi parent and the code for the printpreviewdialog print event for the mdi child.

VB Code:

'This code is in the mdi parent and is used to print a preview of the 
    'currently selected mdi form
    Private Sub mnuPrintPreview_Click(ByVal sender As System.Object, _ 
        ByVal e As System.EventArgs) Handles mnuPrintPreview.Click
 
        'is this the best way to reset the printpreviewdialog?
        PrintPreviewDialog1.Document = Nothing
 
        Dim intPrintAreaHeight, intPrintAreaWidth, marginLeft, marginTop As Int32
        With PrintDocument1.DefaultPageSettings
            intPrintAreaHeight = .PaperSize.Height - .Margins.Top - .Margins.Bottom
            intPrintAreaWidth = .PaperSize.Width - .Margins.Left - .Margins.Right
            marginLeft = .Margins.Left
            marginTop = .Margins.Top
        End With
        ' If the user selected Landscape mode, swap the area height and width.
        If PrintDocument1.DefaultPageSettings.Landscape Then
            Dim intTemp As Int32
            intTemp = intPrintAreaHeight
            intPrintAreaHeight = intPrintAreaWidth
            intPrintAreaWidth = intTemp
        End If
 
        Dim frmCurrent As Form = Me.ActiveMdiChild
        Select Case frmCurrent.Name
            Case "frmCFRReport"
               'pass a print area rectangle to the form
                frmCFRReport.PrintAreaRectangle = New Rectangle(marginLeft, _ 
                marginTop, intPrintAreaWidth, intPrintAreaHeight)
                frmCFRReport.PageSettings = PrintDocument1.DefaultPageSettings
               'set the printpreviewdialog1 to the childform printpreviewdocument
                PrintPreviewDialog1.Document = frmCFRReport.PrintCFRDocument
            Case else
                'Other cases here
        End Select
 
        If PrintPreviewDialog1.Document IsNot Nothing Then
            PrintPreviewDialog1.ShowDialog()
        End If
 
    End Sub

VB Code:

'this is the mdi child form printpreviewdocument print event
    Public Sub PrintCFRDocument_PrintPage(ByVal sender As System.Object, _ 
        ByVal e As System.Drawing.Printing.PrintPageEventArgs) _ 
        Handles PrintCFRDocument.PrintPage
 
        e.Graphics.Clear(Color.White)
        Threading.Thread.Sleep(50)
 
        e.Graphics.DrawString(lblMainHeading.Text, MainFont, TextColour, _
        recPrintArea.Left + lblMainHeading.Left, recPrintArea.Top + _
        lblMainHeading.Top)
        Threading.Thread.Sleep(50)
 
        e.Graphics.FillRectangle(SubHeadingGroupColour, recPrintArea.Left _
        + grpExpenditure.Left + intExpXOffset, recPrintArea.Top + _
        grpExpenditure.Top + intExpYOffset, grpExpenditure.Width, _
        grpExpenditure.Height)
        Threading.Thread.Sleep(50)
    End Sub

Any help would be GREATLY appreciated. I seem to be running around in circles here.