Sign, yet another bootable CD thread. Will someone please write a good explanation and stick it on top of this forum, so at least this kind of problem will not come up at least once every day or so.
Your problem, most likely is that you are trying to iether write an ISO file onto a CD as a file, or creating a bootable cd with that said file. All you need to to is to burn file you have downloaded (which is incidentally has iso extention) as an image. Basically somewhere in your burning app, there is "Burn CD Image" or "Burn File as Image" command, which you should use. Do not, and i repeat do not make the cd bootable using your burning soft. When the iso file is burning it will make it so by itself.