php memory limit group

I am new to open atrium and have just started to work on how to manage permissions via groups and teams. I navigated to a space, created a group and received an error after submitting. The php memory limit was at 256M so I increased to 512M and restarted the web server. Now I cannot access the home page of the site. Here is the error I am receiving:

Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 7 bytes) in /home/mikeg/public_html/hive/profiles/openatrium/modules/contrib/og_subgroups/og_subgroups.common.inc on line 273