Not sure what changed on the system. Red Hat Enterprise apache 1.3.31 php 4.3.3 and 4.3.7 neither work I have 2 other systems identical and zend works fine on those. When trying to install it on this system i get the follow. -bash-2.05b# php -v shmget() failed: No space left on device Failed to start up concurrent users module! PHP 4.3.3 (cli) (built: Jun 14 2004 03:38:43) Copyright (c) 1997-2003 The PHP Group Zend Engine v1.3.0, Copyright (c) 1998-2003 Zend Technologies with Zend Extension Manager v1.0.2, Copyright (c) 2003-2004, by Zend Technologies with Zend Optimizer v2.5.2, Copyright (c) 1998-2004, by Zend Technologies Segmentation fault (core dumped) anyone else have this problem?