The first thing I would do is test that CD in another computer. The odds are strongly in favor of it's being bad media. Also, in case you did not do so, test the downloaded image against the MD5 sum: https://help.ubuntu.com/community/HowToMD5SUM
Is it possible it's stuck on "Loading bootloader" as opposed to "Loading bootlogo"? That would seem more likely, as the bootloader is the first thing that loads.