See possible explanation http://ubuntuforums.org/showpost.php?p=8416402&postcount=4
"I'm not 100% sure what went wrong, but I think this is an issue related to the CD-R disks that I used. If you ever encounter this problem, try to burn the iso-image to a DVD-R disk and try again. On my Nec DVD-drive, TDK and Verbatim 4.7GB DVD-R disks work!" -- Alternate install fails requesting same disc https://bugs.launchpad.net/bugs/360460 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
