I have the restricted format software installed via one-click-install. I found that in 11.4 mplayer would fail to start playing a MP3 clip, but succeed on the second and subsequent tries, but only within a short time afterwards. A quick examination showed that this was because mplayer was firing off an instance of pulseaudio, which stayed around for a while, then exited.
This was not acceptable for a clip played from a cron job so I found the way to bypass pulseaudio for mplayer was by putting this line in ~/.mplayer/config:
Worked fine afterwards. I don’t know if this affects the ability to output audio from other apps while the sound device is in use, but I don’t have that situation, so this workaround suits me.
Take this tip for what it’s worth. If it breaks something, keep the pieces.