从HTML输出的半个html代码，带有十六进制代码bug

I don't know exactly how to explain this but when I POST on my page or when I change a SESSION variable, sometime, not always, I will get half the html in plain text starting with a hexa code. I don't know what to do. Its always random, the hexa code is almost always different.

Exemple :

bc86
    <div>something...</body></html>

If there was a problem of encoding which is mostly possible then you can try the following before producing some HTML/text to client:

header('Content-Type: text/html; charset=utf-8');