APC: "Internal Zend Error" on class definition

I use APC and regularly get the error message "Internal Zend error - Missing class information for in <filename>" (yes, there is only a whitespace between "for" and "in"). The error occurs in arbitrary files and always in lines where a class definition is started: class myclass { ... The error starts when I issue a "graceful" signal to Apache, and for that file I get this error for every call after that, until I send another graceful signal (or restart Apache completely, of course). Settings: APC 3.0.8 PHP 4.4.0 Apache 1.3.33 page hits to PHP files: up to 10/s APC options: apc.slam_defense=90 No other extension is used Is this something known? Any chance to solve that? Thanks in advance!