I have reasons to believe that Drupalchat may be harmful when used in pair with some Drupal modules, such as CiviCRM and the quiz module.
Here's a full bug report for the trouble I reported with CiviCRM until I turned off the Drupalchat module :
I can salvage some more details from our issue queue, if someone is interested in looking more closely at how this problem may fit in with CiviCRM or the quiz module.
I've assumed (perhaps wrongly) that we were facing some race conditions with ajax and PHP sessions, as exposed in the following article :
I do not intend to troubleshoot this issue myself or cause any false emergency, but I've failed to find a documented proof of my hypothesis. My hope is that, if ever someone runs into the same problem, he could end up here, read your educated replies and react accordingly. I'm also curious to read your comments.