Problem with header();

Hi guys, probably everybody goes think: "its the same problem ever" HTML before header() functions ... but it is not. I has working on a project and this are a running in "Windows" (shame on me). Recently i migrate to *Ubuntu *and some problems occurred and that specifically i can't understand WHY this rappening "Warning: Cannot modify *header* information - headers already sent by" On my web server on the internet it's OK On my local web server on my work it's OK On my loca web server on my notebook it's the problem. This error occurs only in my notebook (recently that I migrate to linux and it does not already). Please, someone have any idea what the fuck is happening? Regards, Igor Escobar systems analyst & interface designer www . igorescobar . com