Intermittent problem: can't write to properties of $this

Greetings, I'm currently trying to troubleshoot an intermittent problem on one of our servers. After some time of running just fine (usually a couple of hours), scripts will start throwing the warning "Attempt to assign property of non-object" when writing to a property of the $this object. Once it starts, it seems to keep happening every few requests (with other requests running as expected). The poster at http://www.zfforums.com/zend-framework-components-13/core-infrastructure-19/warning-attempt-assign-property-non-object-zend_config-5469.html seems to be having the same issue. I've traced the warning output to line 576 of Zend/zend_execute.c, which means that something is happening to the write_property of the object. At this point, I don't have enough knowledge of the internals to continue tracking this bug down. Any help would be appreciated. Thanks! Tim Steiner <tsteiner2@unl.edu> Relevant Server Specs: Red Hat Enterprise Linux 4 Apache 2.0.52 PHP 5.3.3 compiled from source with configure line at http://pastebin.unl.edu/1487