usb-creator with user preferences and documents

When selecting the option "user documents and settings be stored on a reserved extra space" the USB is unusable.
About one month ago, pressing escape (which I assume changes to tty0) a message showing that it tries to
 mount /dev/sr0 (which is the real CD-Player on PC)
from some days ago a message:
unable to umount /dev/cdrom
appears.
There is no meaning to send any report since this happen to almost any PC it does not create a log and it does not happen when "discard on shutdown unless you save them elsewhere" is selected.
My thought is that loaded kernel makes "assuptions" about where the reserved extra space is and does not "reverse enginearing" to find where exactly it is loaded from so that it can use that specific /dev to mount (or loopmount?).