Piwik 2.7.0 strangles the server (no replies)

Hello,

Without doing virtually anything, everytime i try to open Piwik the servers dies (entry-process spikes, but no cpu usages).. after several minutes (probably php die-time) those processes will go away and server will again start serving pages.. but whenever i try to open piwik again the same happens, servers dies.. i downloaded fresh piwik 270 zip and reuploaded on site, no effect. I would preffer not to do a clean fresh install and lose all the data.

In server logs i have this over and over again, hundreds of times

16 require_once(...) called at [/home/blissmed/public_html/piwik/index.php:46]<br />
#15 Piwik\FrontController->dispatch(...) called at [/home/blissmed/public_html/piwik/core/dispatch.php:34]<br />
#14 Piwik\FrontController->doDispatch(...) called at [/home/blissmed/public_html/piwik/core/FrontController.php:86]<br />
#13 Piwik\FrontController->makeController(...) called at [/home/blissmed/public_html/piwik/core/FrontController.php:562]<br />
#12 Piwik\Plugin\Controller->__construct(...) called at [/home/blissmed/public_html/piwik/core/FrontController.php:116]<br />
#11 Piwik\Plugin\Controller->init(...) called at [/home/blissmed/public_html/piwik/core/Plugin/Controller.php:119]<br />
#10 Piwik\Site->__construct(...) called at [/home/blissmed/public_html/piwik/core/Plugin/Controller.php:130]<br />
#9 Piwik\Plugins\SitesManager\API->getSiteFromId(...) called at [/home/blissmed/public_html/piwik/core/Site.php:64]<br />
#8 Piwik\Plugins\SitesManager\Model->getSiteFromId(...) called at [/home/blissmed/public_html/piwik/plugins/SitesManager/API.php:185]<br />
#7 Zend_Db_Adapter_Abstract->fetchRow(...) called at [/home/blissmed/public_html/piwik/plugins/SitesManager/Model.php:59]<br />
#6 Piwik\Db\Adapter\Pdo\Mysql->query(...) called at [/home/blissmed/public_html/piwik/libs/Zend/Db/Adapter/Abstract.php:755]<br />
#5 Zend_Db_Adapter_Pdo_Abstract->query(...) called at [/home/blissmed/public_html/piwik/core/Db/Adapter/Pdo/Mysql.php:229]<br />
#4 Zend_Db_Adapter_Abstract->query(...) called at [/home/blissmed/public_html/piwik/libs/Zend/Db/Adapter/Pdo/Abstract.php:238]<br />
#3 Zend_Db_Statement->execute(...) called at [/home/blissmed/public_html/piwik/libs/Zend/Db/Adapter/Abstract.php:479]<br />
#2 Zend_Db_Statement_Pdo->_execute(...) called at [/home/blissmed/public_html/piwik/libs/Zend/Db/Statement.php:300]<br />
#1 PDOStatement->execute(...) called at [/home/blissmed/public_html/piwik/libs/Zend/Db/Statement/Pdo.php:228]<br />
Warning:</strong> <em>PDOStatement::execute(): Error reading result set's header</em> in <strong>/home/blissmed/public_html/piwik/libs/Zend/Db/Statement/Pdo.php</strong> on line <strong>228</strong>