Please give me any suggests!

Hi I'm using some functions about a dom xml. the first one is domxml_xmltree(). I have this error message in error.log of Apache when I ask to my function to call the function domxml_xmltree(). BUT Not always :(. Premature end of scripts headers c:/php/php.exe. I use the imap_bodyfetch to take the xml doc from body mail and i use the imap_base64 or others to encoding the attached doc. I get a right document and I suppose this because I save the document and when I open it I can see it in the browser like a right structure xml. Like I've already told during the reading of some mails(then some xml doc) I have no problems. Sometimes my browser does not complete my request e give this message "INTERNAL SERVER ERROR". At this time I can't go on. Sometimes I have this alert php.exe application error, after the page is displayed in the browser correctly and I can go on. I've downloaded the latest version of libxml but I use PHP Version 4.3.1 and then I have to take only iconv library. And I've downloaded the latest version of it. Kind regards Valentina.