500 Errors caused by Out of Memory

Hi Again,

I am having a hard time getting things to work. I have installed most of your plugins in my multisite and allocated far more memory than the limits allow in my PHP.ini Yet, I can access the admin for a while and then I get 500 errors as I activate the plugins. 98% of the plugins I am using are by WPMU and even when I disable 2% that are not, I still get the 500 Error and all the sites are inaccessible. I was wondering if you could help me out so I can get going once and for all. Here is the latest text from my server’s error log:

PHP Fatal error: Allowed memory size of 52428800 bytes exhausted (tried to allocate 4864 bytes) in /hermes/bosoraweb063/b1343/ipg.soulfulwriter/wp-content/plugins/pro-sites/pro-sites-files/modules/bulk-upgrades.php on line 56

PHP Warning: Unkno

20121201T175647: http://www.soulfulwriters.com/wp-admin/index.php

PHP Warning: session_start(): open(/var/php_sessions/sess_6dd1bba0a489193745b5b5e5d01a5701, O_RDWR) failed: No such file or directory (2) in /hermes/bosoraweb063/b1343/ipg.soulfulwriter/wp-content/plugins/comments-plus/lib/external/facebook/facebook.php on line 37

PHP Fatal error: Allowed memory size of 52428800 bytes exhausted (tried to allocate 77824 bytes) in /hermes/bosoraweb063/b1343/ipg.soulfulwriter/wp-content/plugins/wordpress-chat/wordpress-chat.php on line 1104

How much memory does it take to run these plugins? I’ve allocated 256M already when the max is 64M. I wonder if I should just install separate instances of WP for my sites and run the plugins individually in each site with the sites having their own database.

Thank you for your prompt assistance.

Kind regards,

Barbara