I am running on PHP 5.2.17 on Windows Server 2008 R2 6.1 using PHPDOCX 2.5 free version
examining the code of transformDOC it seems to be the preg_replace function in the foreachloop in generateXHTML giving this error.
looking closer, when printing the contents of the rel file, it ends with PHP had encountered a stack overflow...
I find it very disturbing that you do not use domdocument to the fullest..... you can better use:
$xmlDOM->loadXML($xml);
$xmlDOM = $xmlDOM->getElementsByTagName("body")->item(0); if you just want to get the body!
this last one will fix the stack overflow problem..but still not getting anything on screen...so question still stands!