You're receiving a blank page due to the below errors.
Code:
Notice: Undefined property: cbPluginHandler::$baseurl in /components/com_comprofiler/plugin/user/plug_communitybuilderphocadownloadplugin/phoca_download.php on line 43
This is coming from 3rd party CB plugin "Persoonlijke download" (phoca_download) and have disabled it for you. I've confirmed the notice is now gone from CB > User Management.
Code:
Fatal error: Cannot redeclare uddeimgetusertz() in /components/com_uddeim/uddeimlib15.php on line 29
Fatal error: spl_autoload() [<a href='function.spl-autoload'>function.spl-autoload</a>]: Class JException could not be loaded in /libraries/joomla/error/error.php on line 175
This is coming from 3rd party CB plugin "Private Messaging System (uddeIM PMS)" (pms.uddeim) and have disabled it for you. I've confirmed you can now access backend pages fine.
Your issues are likely due to the fact UddeIM 2.5 is not compatible with J2.5 (it is compatible with J1.7 however). Please upgrade to UddeIM 2.7, which you can download from below.
www.slabihoud.de/software/id4001.htm