so, yet again, after a fresh ubuntu install, I had forgotten that the sound card
on the acer 5100 series does not work correctly. More specifically (at least for me) it only played music from the right speaker.

So, after looking for info for ages, and trying to download the correct drivers (alsa project website down) I finally managed to get them from their ftp address.

HTTP
Alsa Project
alsa-driver
alsa-lib
alsa-utils

FTP
pub (root)
alsa-driver
alsa-lib
alsa-utils

I downloaded the following:
alsa-driver-1.0.14rc3.tar.bz2
alsa-lib-1.0.14rc3.tar.bz2
alsa-utils-1.0.14rc2.tar.bz2

I put these in ~/alsa/

The following information is from two sources:
https://help.ubuntu.com/community/HdaIntelSoundHowto
http://ubuntuforums.org/showthread.php?t=362980
All credits to these guys!!

This is what I did… and hey presto! Sound on both speakers!!

sudo mkdir -p /usr/src/alsa
cd /usr/src/alsa
sudo cp /home/jv2/alsa/* .
sudo tar xjf alsa-driver-1.0.14rc3.tar.bz2
sudo tar xjf alsa-lib-1.0.14rc3.tar.bz2
sudo tar xjf alsa-utils-1.0.14rc2.tar.bz2

cd alsa-driver-1.0.14rc3
sudo ./configure --with-cards=hda-intel
sudo make
sudo make install
sudo ./snddevices

cd ../alsa-lib-1.0.14rc3
sudo ./configure
sudo make
sudo make install

cd ../alsa-utils-1.0.14rc2
sudo ./configure
sudo make
sudo make install

sudo chmod a+rw /dev/dsp /dev/mixer /dev/sequencer /dev/midi

sudo modprobe snd-hda-intel
sudo modprobe snd-pcm-oss
sudo modprobe snd-mixer-oss
sudo modprobe snd-seq-oss

------------------------------------
sudo gedit /etc/modprobe.d/alsa-base
------------------------------------
-------------- add -----------------

options snd_hda_intel model=acer position_fix=1
alias /dev/mixer snd-mixer-oss
alias /dev/dsp snd-pcm-oss
alias /dev/midi snd-seq-oss
alias snd-card-0 snd-hda-intel
alias sound-slot-0 snd-hda-intel

------------------------------------
------------------------------------

sudo rm /etc/asound.*

sudo reboot