You have a structure error there:
/dev/sr0 /media/cdrom0 udf,iso9660 noauto,user,rw 0 0
You can have one of udf or iso9660, but not both. I believe what is happening is that the options (noauto,user,rw) are being ignored and treated as the fifth field (and being 0).
Normally you would not have this in the /etc/fstab anyway. This is usually handled by the udev service as the contents of a CD/DVD can be things other than udf or iso9660.
On second thought, it shouldn't be doing anything during boot... The error should prevent it from mounting.
I would guess udev is actually mounting it.