Error I get when accessing my wp-admin page

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘register_admin_color_schemes’ was given in /public_html/blog/wp-includes/plugin.php on line 339

And then:

Warning: Cannot modify header information – headers already sent by (output started at /public_html/blog/wp-includes/plugin.php:339) in /public_html/blog/wp-includes/functions.php on line 790

Warning: Cannot modify header information – headers already sent by (output started at /public_html/blog/wp-includes/plugin.php:339) in /public_html/blog/wp-includes/functions.php on line 791