vBulletin apparently has a built-in send pm to user function on sign-up, as that's what class_dm_user is calling, and my plugin wasn't written to handle that (at least when the fromuser switch is on - otherwise it doesn't call my code at all in that function). Let's do an experiment and see if this fixes it. Open up the XML and change this line:
PHP Code:
if ($vbulletin->userinfo['posts'] < $arc_exempt_postcount)
to this:
PHP Code:
if (isset($vbulletin) && isset($db) && isset($vbulletin->userinfo) &&
$vbulletin->userinfo['posts'] < $arc_exempt_postcount)
Then reupload the XML and see if you still get errors.