@columboscoat It might be because I followed this guide; http://linuxg.net/how-to-properly-remove-lxde-and-install-xfce-on-raspbian-debian-for-raspberry-pi/ which has you remove LXDE and then install xfce, but the thing is I've followed that before and I could always just startxfce4 fine afterwards, maybe something to do with a newer retropie version removing lxde breaks this method?

will try again without doing that, just wanted to slim things down as much as possible.