Network settings not working with this plugin

Hello, since wordpress version 3.7 and even in 3.7.1 I get an error like
Call to undefined function wp_get_current_user() in /var/www/web116/html/wp-includes/capabilities.php on line 1286 when I go to my network-settings. The PlugIn itself works, but I get this error. If I rename the plugin-folder, it works again, I can update everything and so on. But that is no real solution…

Greetings,
Drongo

http://wordpress.org/plugins/proper-widgets/