404 error

Hello, when I clock Update (WP or any plug) i have 404 error - not found.
I had previously wordpress 3,7 but now I have WP 3,8 and it happens the same.
My page: www.mks-gorce.pl

I can't find the corrupted page. Could you give me the URL of the page?

or http://www.mks-gorce.pl/wp-admin/update.php?action=upgrade-plugin&plugin=cyclone-slider-2%2Fcyclone-slider.php&_wpnonce=0f12a2883d

When I click refresh 2, 3 times this page load normally.

Hi!
Sorry, but still can't find the link to this page on you website.