Dpgk

http://askubuntu.com/questions/15433/how-do-i-fix-a-could-not-get-lock-var-lib-dpkg-lock-problemYou will get this message if you forget to use sudo when executing an apt command.
Otherwise this is a sign that something else is installing or removing software and has locked the apt database while it performs the actions. The programs that can do this are:
* The Software Center
* The Update Manager
* The apt link installer (I think this now goes through SC)
* The apt-get or aptitude command line utilities.
https://help.ubuntu.com/community/PackageManagerTroubleshootingProcedure