Strange Problem

Hi all, this is a very strange problem. i don't know where i am doing something that is causing this. the problem is that i am working on a web portal entirely in php. i have a few hidden pages. that do the queries to the DB. now when i redirect to any page for query i get this error CGI Error The specified CGI application misbehaved by not returning a complete set of HTTP headers. The headers it did return are: strangely when i hit F5 or refresh the page i get redirected to the desired page. i have checked for any whitespaces. there are none. i have checked and double checked this. i am using win2k,IIS, php 4.3.0 again i have checked all the files for any space left that could be causing problem but i found none. i hope i make my self clear. Haseeb