This notice shows up in WP 3.3.1 with v1.0.2 when WP_DEBUG is enabled.
Notice: wp_enqueue_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or init hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.) in /var/www/vhosts/[redacted]/httpdocs/wp/wp-includes/functions.php on line 3587
http://wordpress.org/extend/plugins/simpletest-for-wordpress/
Thanks Ian - I will correct this. I found this example for it: http://wpfirstaid.com/tag/wp_enqueue_scripts/
If you enable the Debug Bar plugin, you can see some other warnings being issued:
WARNING: wp-content/plugins/toppa-plugin-libraries-for-wordpress/ToppaAutoLoaderWp.php:39 - include(/var/www/vhosts/[redacted]/httpdocs/wp/wp-content/plugins/toppa-plugin-libraries-for-wordpress/WP/User/Search.php): failed to open stream: No such file or directory
WARNING: wp-content/plugins/toppa-plugin-libraries-for-wordpress/ToppaAutoLoaderWp.php:39 - include(): Failed opening '/var/www/vhosts/[redacted]/httpdocs/wp/wp-content/plugins/toppa-plugin-libraries-for-wordpress/WP/User/Search.php' for inclusion (include_path='.:/usr/share/pear:/usr/share/php')
WARNING: wp-content/plugins/toppa-plugin-libraries-for-wordpress/ToppaAutoLoaderWp.php:39 - include(/var/www/vhosts/[redacted]/httpdocs/wp/wp-content/plugins/simpletest-for-wordpress/WP/User/Search.php): failed to open stream: No such file or directory
WARNING: wp-content/plugins/toppa-plugin-libraries-for-wordpress/ToppaAutoLoaderWp.php:39 - include(): Failed opening '/var/www/vhosts/[redacted]/httpdocs/wp/wp-content/plugins/simpletest-for-wordpress/WP/User/Search.php' for inclusion (include_path='.:/usr/share/pear:/usr/share/php')
It complains about files missing from your library plugin, even though it's installed and activated.