CGI-Trouble with Win2000

Hi, we've a lot of trouble using PHP on IIS5/Win2000sp2-Server. The machine is a 2xPIII(1,3Ghz), 1280MB RAM, really fast. The problem is that sometimes the IIS doesn't execute the php.exe, instead it shows a "CGI Application error - wrong or incomplete header data...." This problem only occurs on this fast server and only with a website that uses frames. I suppose that the IIS launches different threads to render the frames and isn't able to do the IO to the php.exe for every thread. To test this we wrote a little script wich shows 12 Frames, filled with a little PHP-Skript that only shows one line of text. On the slow machine theres no problem. On the fast machine, same software, we get the cgi-error in round about every 50th or 60th frame (refresh..) Thanks for any hint. Regards, Jan Schmitz