I've installed Apache2 and PHP5 via apt-get on Ubuntu 14 (amd64), Tomcat 6, and Postgres 8.4. I get this error message on an attempted restart: 

```
apache2: Syntax error on line 140 of /etc/apache2/apache2.conf: Syntax error on line 1 of /etc/apache2/mods-enabled/php5.load: Cannot load /usr/lib/apache2/modules/libphp5.so into server: /usr/lib/apache2/modules/libphp5.so: symbol xmlOutputBufferGetSize, version LIBXML2_2.9.0 not defined in file libxml2.so.2 with link time reference

```

I've removed/purged and reinstalled apache, php, and libapache2-mod-php5 to no avail. 

Any thoughts on getting this working?