bitmap.save and the dredded "A generic error occurred in GDI+."

[haydena]

I'm trying to insert a page and then apply some text to each page of a multi-page tiff.

If I just want to insert a page without applying any additional text to each page, this code has been working fine:

'some stuff to insert the cover

'loop through each page of the multi-page tif
Dim byteStream As New MemoryStream()
Dim count As Integer = bitmap.GetFrameCount(FrameDimension.Page)
            For idx As Integer = 0 To count - 1
                bitmap.SelectActiveFrame(FrameDimension.Page, idx)
                bitmap.Save(byteStream, ImageFormat.Tiff)
                images.Add(Image.FromStream(byteStream))
            Next

'some stuff to process and save a tif

This is the code I'm using to insert the cover and add additional text to each page:

'some stuff to insert the cover

'loop through each page of the multi-page tif
Dim byteStream As New MemoryStream()
Dim count As Integer = bitmap.GetFrameCount(FrameDimension.Page)
        For idx As Integer = 0 To count - 1
            
            bitmap.SelectActiveFrame(FrameDimension.Page, idx)

            Dim bitmap2 As New Bitmap(bitmap)
            bitmap2.SetResolution(300, 300)

            Dim g As Graphics = Graphics.FromImage(bitmap2)

            Select Case Trim(Type)
                Case Is = "X"
                    Dim rectf As New RectangleF(2100, 75, 300, 75)
                    g.DrawString(DocNum, New Font("Arial", 10), Brushes.Black, rectf, stringFormat)
                Case Is = "Y"
                    Dim rectf As New RectangleF(2100, 150, 300, 75)
                    g.DrawString(DocNum, New Font("Arial", 10), Brushes.Black, rectf, stringFormat)
            End Select

            bitmap2.Save(byteStream, ImageFormat.Tiff)

            images.Add(Image.FromStream(byteStream))

            g.Dispose()
            bitmap2.Dispose()

        Next

'some stuff to process and save a tif

With larger images, I get "A generic error occurred in GDI+." "[ExternalException (0x80004005): A generic error occurred in GDI+.]" at bitmap2.Save(byteStream, ImageFormat.Tiff) once I hit about the 20th image. Any thoughts as to what the issue is and how I might resolve it?