David Bogner posted to the forum on Friday, 28 August 2009 that...

"when i submit a text (create a new dialogue or submit a message to an existing dialogue) I get following error code:
Catchable fatal error: Object of class stdClass could not be converted to string in pathtomoodle/lib/moodlelib.php(5462) : eval()'d code on line 1
I am working on moodle 1.9.5+ and installed the module from the modules and plugin database for version 1.9."

TimH suggested this could be a language string issue where an object is passed when only a string is expected