Hmm, this sounds like maybe a file wasn't uploaded. Can you check in your templates/default directory and look at the sendprivate.tpl file. If you have the latest uploaded you should see this at the start:

Code
{* Script Version 7.0.2 *}
<script language="Javascript" type="text/javascript">
var dupUser = "{$lang.ALREADY_ADDED}";
var tooMany = "{$lang.TOO_MANY}";
var pmLimit = "{$config.PM_PARTICIPANTS}";
</script>

Last edited by Rick; 12/29/2006 2:58 PM. Reason: Edited, because I'm a moron