I'm having a weird problem, where I can connect to Solr, and index the site (I can search on the Solr Admin area for the indexed content, and it works), but when I search in Drupal, I get the error:

The Apache Solr search engine is not available. Please contact your site administrator.

Does anyone know why this would happen? I can clear connect to Apache Solr, so I'm not sure why this would happen. The error I get in the logs is
"0" Status: Communication Error

which is in no way helpful to me.