Just to throw my hat in,
I had a problem with this same type of issue on my Hd install. How I got aroung it was by deleting the desktop icon for the cd rom on my desktop. I then rightclicked and created a new device. I named it cd-rom and selected the device from the list it provided me. It worked for me. I know it doesn't change the config setting and delve into the core but you may want to try it.

If it doesn't work, sorry can't help.