page cannot be displayed after a post of form with over 80 post elements

hi guys, i am facing the above problem. i couldn't explain whats causing this behavior. however, those data does get posted to the server. only thing is that the result page is not showing up but the above error page. i have tested with 60+ post elements, but no error of such occur. any idea what could be the cause? platform: win2k, sp3 iis5 php on cgi i have been wondering if it is iis5 that is giving the problem. thanks, lance