500 internal server error
 

So I woke up this morning to a 500 Internal Server Error on my forums:

http://www.thegrubs.com

I looked at the error log and notice a bunch of these:

[Sun Oct 04 00:28:24 2009] [error] [client x.x.x.x] Premature end of script headers: index.php
[Sun Oct 04 00:28:24 2009] [error] [client x.x.x.x] File does not exist: /home/thegrubs/thegrubs.com/internal_error.html

So I backtrack and the first mention of this particular error looks like this:

[Sun Oct 04 00:01:44 2009] [error] [client x.x.x.x] Premature end of script headers: cron.php* referer: http://www.thegrubs.com/forums/login.php
[Sun Oct 04 00:01:44 2009] [error] [client x.x.x.x] File does not exist: /home/thegrubs/thegrubs.com/internal_error.html* referer: http://www.thegrubs.com/forums/login.php

So the first thing I do is FTP into the site and copy down all the files as a backup. Then I reupload all the original vbulletin files* except for the image directory. I go to the includes/config.php file and add "define('DISABLE_HOOKS'* true);". I try to then hit the front page of the site and still get the internal server error.

I start checking all the other hosted sites I have with this host and they are all fine. Database access works as well on the other sites. The problem does not appear to be host related nor MySQL related.

Any ideas on where to look? Does the 'disable hooks' command disable vbadvanced? I'm only running a few addons (AME* TCattd image resizer* and vbadvanced).

I've put in a support request to my hosting company* but haven't heard back yet* but since other hosted sites are fine* I'm pretty sure the problem is in vbulletin somewhere. I'm hoping someone here can shed some light.

EDIT to add add'l info:

I've noticed that most of the php files for the site are set to 644 permissions. Most of the googled sites I can find on this problem say that scripts should be 755. Should I change them? Or is 644 correct?