PHP error fix

I am getting an error of "**Warning**: Cannot modify header information - headers already sent by (output started at /home/djxkon/public_html/[login to view URL]) in **/home/djxkon/public_html/[login to view URL]** on line **23**" The hosting company wasn't any help, I've searched the internet for answers, most people say there must be spaces some where at the end of the code or some html somewhere. I have searched the code again and again, and can not find the problem. I am getting this error on several pages througout the site, I need someone to dig through the code, find the error and fix it, site wide, shouldn't be more than 10 pages to look through.