Fatal error with some Posts

Hello,

I installed your plugin on my blog: but after, some post’s didn’t want to open (like this post: http://www.inwestycjewinternecie.pl/paidverts-platforma-reklamowa-ktora-dzieli-sie-zyskami-hit/ – now I turned off plugin because was no access to this post). When is ON I recive this messages:

Fatal error: ob_end_flush() [<a href='ref.outcontrol'>ref.outcontrol</a>]: Cannot use output buffering in output buffering display handlers in /home/hosting/domains/inwestycjewinternecie.pl/public_html/wp-includes/functions.php on line 3269

This is a code from functions.php since line 3259-3272.

/**
 * Flush all output buffers for PHP 5.2.
 *
 * Make sure all output buffers are flushed before our singletons are destroyed.
 *
 * @since 2.2.0
 */
function wp_ob_end_flush_all() {
	$levels = ob_get_level();
	for ($i=0; $i<$levels; $i++)
		ob_end_flush();
}

/**

Whan can be wrong? When I remove everythinh inside the post its same problem.

Thanks for a help.

https://ww.wp.xz.cn/plugins/wp-retina-2x/