Error Message in Top bar

Hello,
I’m creating a test site for my website, and after cloning it to a second test site, I’m getting this error message.
It appears intermittently, and creates a large grey area in the top header…
Can you please help?
Thank you!

http://obw.pinkteacups.com

Strict Standards: call_user_func_array() expects parameter 1 to be a valid callback, non-static method sidebar_generator::init() should not be called statically in /home/journalg/public_html/hello/wp-includes/plugin.php on line 470

Strict Standards: Non-static method sidebar_generator::get_sidebars() should not be called statically in /home/journalg/public_html/hello/wp-content/themes/HighendWP/admin/plugins/multiple-sidebars.php on line 53