I had installed a non-ubuntu distribution of python (stackless python). This became the default python installation used by the system, but was located in /usr/local/bin/python not /usr/bin/python, so the path to all the other modules was wrong.
To fix, I renamed the stackless python version from /usr/local/bin/python to /usr/local/bin/spython. I now have 2 python installations and the system picks up the default installation. Perfect.
I found the solution to this on my system.
I had installed a non-ubuntu distribution of python (stackless python). This became the default python installation used by the system, but was located in /usr/local/ bin/python not /usr/bin/python, so the path to all the other modules was wrong.
To fix, I renamed the stackless python version from /usr/local/ bin/python to /usr/local/ bin/spython. I now have 2 python installations and the system picks up the default installation. Perfect.