Download Protected File Duplicate

(This has been taken from the older forums and reposted with updates to make it easier to follow – hope that’s ok) *** Denotes updated part.
Hey, the plugin is working all in all pretty good. Here is my setup:

WordPress ver 3.3.1
s2Member Pro ver 111220
Server Type: Debian
MySQL ver 5.0.45
PHP ver 5.2.17
and using Powweb Hosting (powweb.com)

I can successfully download protected files from the /s2member-files/ root directory and it’s sub files from sub folders etc. Using the latest Safari (on Mac OS X) and the latest IE (on Windows). However can’t download these protected files using the latest FireFox and Chrome on Mac OS X (or FireFox running on Windows).

This is what I’m getting for an error response in Chrome (mac os x):

Duplicate headers received from server
The response from the server contained duplicate headers. This problem is generally the result of a misconfigured website or proxy. Only the website or proxy administrator can fix this issue.
Error 346 (net::ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_LENGTH): Multiple distinct Content-Length headers received. This is disallowed to protect against HTTP response splitting attacks.

and this is the response in FireFox (mac os x):

Corrupted Content Error
The page you are trying to view cannot be shown because an error in the data transmission was detected.

***I’ve tried to resolve using some suggestions from here: http://www.primothemes.com/forums/viewtopic.php?f=4&t=2690&p=7858&hilit=download+duplicate#p7858 but no luck. As for the .htaccess files edit resolve… Interestingly, my .htaccess file in the main wordpress directory is:

RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

However, when changing it to the .htaccess for the main wp directory Jason had given, it sort of killed my site making it unable to visit other pages besides the front/ index page. So I switched it back to what’s shown above. The .htaccess file contents of the /s2member-files/ folder was the same as the .htaccess Jason had provided in that above post.

***I also tried the creating the s2-hacks.php (to disable chunked and flushed file delivery) file in wp-content/mu-plugins/s2-hacks.php but it gives me back this craziness spit out in ALL my browsers on mac os x:

Warning: Cannot modify header information - headers already sent by (output started at /hermes/web08/b1670/pow.zensai/htdocs/nsb/wp-content/mu-plugins/s2-hacks.php:1) in /hermes/web08/b1670/pow.zensai/htdocs/nsb/wp-content/plugins/s2member/includes/classes/files-in.inc.php on line 336

and that’s for that php file lines 336 – 345 and 378 it says it.
I did so both with PHP Execution plugin activated and deactivated. I tried the 4 permutations of combinations for that as well (that is chunked disabled only, both, and flushed disabled only, neither).

*** I also do have the structure of

/wp-content/plugins/s2member/s2member.php

for my s2member install… as the above linked post questioned as well.

*** I have the following plugins:
Akismet (deactivated)
Blubrry PowerPress
Disable Parent Menu Link
GD Star Rating
Google Analytics for WordPress
Jetpack by WordPress.com (deactivated)
Menus
PHP Execution
s2Member
SplashScreen
Subscribe Sidebar (deactivated)
Ultimate Category Excluder
Under Construction (deactivated)
Wiziapp (deactivated)
WP Show IDs
*** I believe none pose any compatibility issues correct? Perhaps it’s because my example-domain.com actually points to a a subfolder in my hosting directory, so.. not /htdocs/ but it points to /htdocs/sub-folder/ as that is where my WordPress install is. Could that be the problem?… probably not right… I mean I am able to download the protected files using Safari (just not FireFox or Chrome).

Should I reinstall s2member??…