I'm a bit lost in that.
I was testing some code, added a couple of changes, then dropped to test it again and... php started outputting pieces of file at the beginning of the page... 
Things like:
],$nname,time(),$filesize),
array());
}
}
}
?>
}
?>
The file is perfectly fine. No syntax errors. The closing tag is properly placed. There are no comments. If I access it directly it doesn't show anything.
emanuele is confused...
It seems I got 5.4 "recently" (I was still 5.3 until... a while ago), dunno when exactly.
ETA: meh, temporarily solved using my usual external directory and a symlink...