If iso9660 works leave off the auto instead so it doesn't have to get autodetected every time.
Also it doesn't have to be scd0. Do "dmesg |grep scd", "dmesg |grep sr", "dmesg |grep CD" to see where your cd is connected to. You can then use it as dev in fstab instead of symlinking the device.
EDIT: Forgot, these work for me:
/dev/sr0 /cdrom iso9660 defaults,ro,user,noexec,noauto 0 0
/dev/sr1 /cdrom1 iso9660 defaults,ro,user,noexec,noauto 0 0