If you ever installed Python's eTiny module for OpenERP, you might want to remove it to install another version. In this case, the solution is to delete the eTiny module's directory (in /usr/lib/python2.4/site-packages for example).
cd /usr/lib/python2.4/site-packages/ rm -r eTiny-1.0.1.1-py2.4.egg/ vim easy-install.pthand remove the line importing the eTiny module.
