CGI-Application-Error on 1% of pagehits...

Hi folks, we try to run PHP as CGI on a Win2000SP2(IIS5)-Sever. On round about every 100 pages we get a HTTP-Error500 (CGI-Application Error, CGI-Server doesn't return a complete set of http-headers). At the beginning we thought this is just another problem with PHP. But then we wrote our own simple CGI-Module that just returns a HTTP-Header and a simple text. The result of this cgi-module is that we get the same error. Then we wrote a skript for the 500-Error which refreshes the site. This works fine in most cases but sometimes the IIS has its "strange 5 Minutes". In this time the server doesn't execute CGI and is only able to send the messages. Everything the skript does in this case is to refresh the Error-Message - which isn't really a solution;) This problem is only reproduceable if SQL2000 is installed on the server. I searched the MSDN for an article about this but can't find anything. In fact this is no PHP-Specific problem this isn't really the right place to post this, but does anyone know whats going on here? Thanks for every hint, Jan