Thumbnail creation in ASP.Net: System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI

how to resize large number of images in a folder  in c# windows application. I am using following code to resize images of my folders. If images are less than 1600 ( in number) then no proble but if images are more than 1600 then i am getting error. My code is given below:-

 public static Image ResizeImage(string file, int width, int height, bool onlyResizeIfWider)
        {           
                using (Image image = Image.FromFile(file))
                {
                    // Prevent using images internal thumbnail
                    image.RotateFlip(RotateFlipType.Rotate180FlipNone);
                    image.RotateFlip(RotateFlipType.Rotate180FlipNone);

                    if (onlyResizeIfWider == true)
                    {
                        if (image.Width <= width)
                        {
                            width = image.Width;
                        }
                    }
                    int newHeight = image.Height * width / image.Width;
                    if (newHeight > height)
                    {
                        // Resize with height instead
                        width = image.Width * height / image.Height;
                        newHeight = height;
                    }
                 

                    Image NewImage = image.GetThumbnailImage(width, newHeight,null,IntPtr.Zero);
                    return NewImage;                 
                }            
        }