Advanced Theme Switcher crashes WordPress

Tried to install advanced theme switcher both via wpmudev installer and the standard wp upload.

Wordpress - view site and wp admin crash.

Here's the error: HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

error log: [04-Jun-2012 15:09:25] PHP Fatal error: Call to a member function get() on a non-object in /home/mylogin/public_html/wp-includes/query.php on line 27