I am running into a similar problem.
Once I corrected a write issue on configuration.php, disabled, then re-enabled PHP, I see the following:
Site > System Information > PHP Information says:
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies
with the ionCube PHP Loader v4.2.2, Copyright (c) 2002-2012, by ionCube Ltd.
on top of PHP v. 5.4.7.
The CommunityBuilder User Manager now opens without the 500 error, but front end Edit Profile and a User List on the front end both throw 500 errors.