You don't check the md5sum after buring the ISO, but BEFORE you burnt it. download the iso image. download the md5sum file (now both of them in the same directory) md5sum -c the_md5_sum_file If no error related to the downloaded ISO was reported, burn it at the speed that your burner could handle. Use a reasonably good brand of disc. <div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">I'm having trouble with md5sums of cd's I burn -- they seme to be burning pretty well but the sum is not identical to that of the iso. I wonder whether I odn't understand md5sum properly? I do: cdrecord --dev=ATA:1,1,0 --speed=12 -tao /path/to/breezy.iso md5sum /dev/hdd /path/to/breezy.iso </blockquote></div>