Problems upgrading Ubuntu Karmic to Lucid

While overall smooth, a couple of details had to be fixed after upgrading Ubuntu Karmic to Lucid:

• Grub didn't automatically select the previous OS I started, as before:

Had to add "GRUB_SAVEDEFAULT=true" to /etc/default/grub (and run update-grub after).

•  The message "An error occurred while mounting /media/cdrom0/
  Press S to skip mounting or M for manual recovery" at every boot, and being unable to mount the CDROM as a normal user:

The CDROM settings in /etc/fstab were missing "noauto" to prevent it from being mounted on boot, and "users" for normal users to be able to mount it.  The result was:

 /dev/scd0       /media/cdrom0   udf,iso9660 utf8,users,noauto 0       0

•  PulseAudio not starting, so audio is not working in most apps

Running the script used to start PulseAudio (in Startup Applications) by hand provided little information:

$ bash -x start-pulseaudio-x11
+ set -e
+ '[' -z '' ']'
+ '[' x:0.0 '!=' x ']'
+ /usr/bin/pactl load-module module-x11-publish display=:0.0
Connection failure: Connection refused

 The problem was finally found in the comments in /etc/default/pulseaudio.  I had disabled PulseAudio's autospawn (as to be able to kill it and start jackd) in my ~/.pulse/client.conf, which is now required for start-pulseaudio-x11.  Enabling it back made it all good (jackd works without having to kill PulseAudio now).