OK, I have created a WordPress 3.6.1 server running PHP 5.4.10 (pretty close) and installed the Placester plugin from wp.org and cannot recreate that error. I was hoping you might say that you were on a budget host, but that doesnt seem to be the case. At some point your server is deleting or changing a file. So can you verify the contents of a file for me. After installing the plugin, go to the Placester plugin directory, then blueprint/functions/core.php. Copy and paste the code from line 115 to 143 here so we can see whats going on.
Alternatively, visit placester.com and click the little green chat button that should be at the bottom of the page. Tell them that Matt sent you and you need to talk with me. They should know what you are talking about. I would have preferred to just put my phone number or email address here, but the WordPress folks don’t like that…