Try to add the following in your .htaccess file: php_value max_execution_time 30000
(the number is the number of seconds).
If that does not work either (some hoster forbid this as well), try to add the following to the index.php: ini_set ('max-execution_time', '30000' )
Be sure to add this after the line ob_start() as otherwise you might get problems with sent headers.
Apart from that - if you try to access the admin part of a site with lots of nodes, the problem might be caused by the menu on the lefthand side. Depending on the settings in contentstructuremenu.ini.append.php EZ might try to fetch all nodes on the site. So change the settings there if necessary. Infos about this here: http://ez.no/doc/ez_publish/technical_manual/3_8/reference/configuration_files/contentstructuremenu_ini
