Debugger again...

Excuse me if I insist, but no one have set up the debugger in the WORLD ? =) If you can help me please reply to my previous post... I have a site which makes "random" errors (pages which sometimes are empty and sometimes allright, with the same input!)... I think that the parser sometimes crashes, because the HTML before the first <?php tag is shown in some pages, and then no more output is given by the server (which doesn't crashes -- no error logs). Any suggestion? Thanks in advance Cesare