Try:

/dev/cdrom /cdrom iso9660 defaults,ro,user,noexec,auto 0 0
# partitions found by Knoppix
/dev/hda1 /mnt/hda1 ntfs auto,users,exec,ro,uid=knoppix,gid=knoppix 0 0

Don't try changing the ro! And make a back up first.

Note that sometimes running automount isn't a good idea!