Comment 2 for bug 283187

Setting up apache2.2-common (2.2.9-7ubuntu3) ...
ERROR: Module alias not properly enabled: /etc/apache2/mods-enabled/alias.load is a real file, not touching it
dpkg: error processing apache2.2-common (--configure):
 subprocess post-installation script returned error exit status 1

This means you had /etc/apache2/mods-enabled/alias.load lying around from a previous install, you put it there yourself (the package itself only puts symlinks in *-enabled), and now a2enmod is confused. Probably a2enmod should not exit with an error in this case, I will think about it.

You can fix the problem by removing that file (and any other files in the same directory).