Search Returns Empty Rows

Search for contacts returns a table with empty rows (contact information is blank on each row).

This is the main symptom of compatibility issues between CiviCRM and an older version of the Zend Optimizer utility. You may also see the following error if you try to edit or view the apparently blank contact record:

Fatal Error: Call to a member function on a non-object...

CiviCRM is fully compatible with the current release of Optimizer - 2.5.10.
However, CiviCRM will not run with Zend Optimizer release 2.5.7.
Instructions for determining whether your server is running Zend Optimizer, and which version, can be found in the instructions Install 2.0 for Drupal Manually.