I experienced the problem with my Ubuntu 12.04 installation a couple of days ago related to the updating process. The error message was:

Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)

If you have the same problem here are the steps that could solve the issue

Method 1

Restart the system and try again

Method 2

If restarting doesn't help, try refreshing package source list

Method 3

Run the following commands

sudo rm /var/lib/apt/lists/* -vf

sudo apt-get update

Method 4

Try with the following command

sudo apt-get update && sudo apt-get upgrade

Method 5

If neither of the steps mentioned above don't work, check if the update process is already running, kill it and try again