[ubuntu] DVD not mounting/unmounting correctly

Hello,
This is similar to some other problems reported but the details of the symptoms are different and other posts I've looked at haven't resolved the problem for me. I can get a DVD to play (including commercial DVDs with restricted codecs) but the steps necessary to do this are not quite right. I suspect I've messed up the fstab.

I have a fresh Ubuntu 16.04 install. Here are some stats:

uname -a
Linux oldHP 4.4.0-22-generic #39-Ubuntu SMP Thu May 5 16:53:32 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

lshw | less
...
     *-cpu
          product: AMD E-350 Processor
...
        *-cdrom
             description: DVD-RAM writer
             product: DVDRAM GT31L
             vendor: hp
             physical id: 0.0.0
             bus info: scsi@1:0.0.0
             logical name: /dev/cdrom
             logical name: /dev/cdrw
             logical name: /dev/dvd
             logical name: /dev/dvdrw
             logical name: /dev/sr0
             version: MR52

## DVD
/dev/sr0    /media/carol/cdrom0    udf,iso9660    ro,user,noauto    0    0

1. The DVD spins up, an icon appears on the launcher bar, but instead of the correct CD/DVD symbol it is the symbol that stands for a hard drive (similarly if nautilus is open it appears in the list of devices as a hard drive).
2. Right clicking the hard drive icon and selecting "open" makes the drive spin up, the icon tus into the correct CD/DVD icon and it opens in nautilus.
3. Nautilus has a "Videos" button in the top right coer (is that new - I've never noticed it before). Clicking that makes the DVD play correctly.
4. When ejecting the DVD (either right clicking the icon on the launcher bar or via nautilus) it requires authorization saying:

"Authentication is required to unmount hp DVDRAM GT31L (/dev/sr0) mounted by another user"

So, I can play DVDs, but it isn't working the way it is supposed to. Any help would be much appreciated.