I went to burn a DVD earlier with Imgburn and I got a buffer underrun when I tried burning on the fly. So I built an ISO image and then burned that and it burned fine. Both times the disc verified correctly, but the md5 of the on-the-fly session did not match the md5 of the image burning session. All files and attributes were identical with both sessions.
Is this something to worry about? Is there any data corruption going on here or does building an image simply change something small?