Got the following message on my beta installation when I clicked on Private Messaging:
Warning: Division by zero in (path)/test/theme/default/pmsg.php on line 952
Statement in question is:
$percent_full = ceil($disk_usage / $ms * 100);
People probably won't run into this often; it would only happen if there are no PMs. Also, it still brings up the page correctly; the warning message is just displayed at the top.
Edit: I think this might have been a problem with my Globals file -- nevermind