What do you mean by "does not seem to function well"? Moodle is probably the most widely adopted open source solution at the moment and thus has a dynamic development and user community, though I realise that Moodle's way of organising courses is not to everybody's taste.
edutools.info provides good information about all sorts of LMSs, including open source solutions. Other established open source LMSs are sakaiproject.org, claroline.net, ilias.de or atutor.ca
Or have a look at social networking tools, such as the above-mentioned elgg.org or ning.com
Best wishes,Tim

There is a new one just released here in New Zealand http://mahara.org/
I haven't tried it yet as I need to find someone to set it up on a webserver.  Got good press here and has single signon capability with Moodle ie you login to mahara and it will allow you to access moodle.
 

Have a look at Elgg or Odijoo
Regards, Paul
http://twitter.com/simbeckhampson

What problems do you have with moodle. I used it for a few years and never had problems. Is there anyhting in particular that did not work for you?
Marian