memory corruption with 5.1?

I've run into a problem, when trying out 5.1.0b1, b2, and php5-200507060230, with a script of mine that relies pretty heavily on DomDocument and DomXPath. Using XPath, I pull nodes with a certain namespace (xx) from an xml document. With 5.0.*, this works as expected. However, with 5.1.*, I'm getting what appears to memory corruption(?) of the DomNode localName property. Previously echo $node->nodeName; echo $node->localName; would yeild xx:nodename nodename With 5.1, I'm getting instead xx:Õ¤9domN9dš9Øû Õ¤9domN9dš9Øû In reducing the operations to a simple: $string = '<root xmlns:xx="xx"><xx:nodename /></root>'; $dom = new DomDocument; $dom->loadXML($string); foreach ($xpath->query('descendant-or-self::xx:*') as $node) { echo $node->nodeName; } ... i don't get the corrupt node names. Only when used in the larger application framework do I run into the problem. I'm at a loss as to how to further troubleshoot this. And as the script isn't causing a segfault, I don't really know what other information to provide, or where to look. Any pointers or help with this would be much appreciated. -james