Basically, problem is described in topic title.
Environment data: I'm running ZP-1.4.5.5 (current version for this moment) on nginx/1.4.3 with PHP-FPM (PHP 5.3.3), located on CentOS 6. Active theme is "Default", but uses custom CSS file with some changes.
But when I'm trying to change "Standard options" (Admin -> Options -> Theme -> Albums) gallery behavior is quite strange. I have "Thumbnails per row" set to "3" and "Thumbnails per page" set to "9". When I'm trying to change these values, scripts posts data to .../admin-options.php?action=saveoptions with correct parameters, got from form, for example, 5 and 10, respectively. I got "Changes saved" or smth similar and... yes, old values!
Strange for me: request to .../admin-options.php?action=saveoptions ends with status code 302 Moved Temporarily. But response URL is "?saved&tab=theme&optiontheme=default".
Actually, any option reverts to "default" on this page, I got no errors but I can change just nothing. Any ideas?