Conflict with Paid Membership Pro

There seems to be a conflict with Paid Membership Pro as well. Here is the error.

Warning: session_start(): Cannot send session cache limiter – headers already sent (output started at /home/../public_html/wp-content/plugins/bbpress/includes/common/functions.php:1199) in /home/../public_html/wp-content/plugins/paid-memberships-pro/paid-memberships-pro.php on line 23

– WordPress up to date? Yes, 3.5.2
– NextGEN up to date? Yes v2
– What version of NextGEN Gallery did you upgrade from? (i.e. I had 1.9.8, then upgraded to 1.9.12) 1.9.13 to 2.0

(please confirm the following, with your server host tech) :
– MySQL up to date (at least 5.2.4)? Yes – Server info below
– PHP up to date (at least 5.0)? Yes – Server info below
– The mod_rewrite Apache module activated? Yes
– PHP Safe Mode OFF?

Additional information that will help us find a solution:
– Who are you hosted with? MyHosting VPS
– What theme are you running? Atahualpa
– Which plugins do you have installed and activated? Only issues were with bbPress and Paid Membership Pro.
– Does this error still occur if you switch your theme to the WP default, and deactivate all plugins except NextGEN Gallery? (*be sure to clear your browser cache and reload your site after deactivating) Did not test. Immediately rolled back update when errors appeared.

Server Info
Operating System : Linux (64 Bit)
Server : Apache/2.2.24 (Unix) mod_ssl/2.2.24 OpenSSL/1.0.0-fips mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635
Memory usage : 36.5 MByte
MYSQL Version : 5.1.70-cll
SQL Mode : Not set
PHP Version : 5.4.15
PHP Safe Mode : Off
PHP Allow URL fopen : On
PHP Memory Limit : 256
PHP Max Upload Size : 16M
PHP Max Post Size : 8M
PCRE Backtracking Limit : 500000
PHP Max Script Execute Time : 30s
PHP Exif support : No
PHP IPTC support : Yes
PHP XML support : Yes
Graphic Library

GD Version : bundled (2.1.0 compatible)
FreeType Support : No
T1Lib Support : No
GIF Read Support : Yes
GIF Create Support : Yes
JPEG Support : Yes
PNG Support : Yes
WBMP Support : Yes
XPM Support : Yes
XBM Support : Yes
JIS-mapped Japanese Font Support : No

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