If you can't CHMOD the file to 444 or above, it may well be that it's CHOWNed to another user (such as "nobody").
I have a script that allows CHMODing files that are owned by nobody (which is what files that are owned by Apache are generally "owned" by).
I had this problem before, and this script helped me sort it. If this is your problem, just download the attached file and read the included nobody.html file to learn how to use it.
Edit: When a moderator approves the attachment, that is.