Craft constantly logging out from admin area
My solution is to add:

'overridePhpSessionLocation' =&gt; false


Into craft/config/general.php

This tells Craft to use the default location to write sessions, instead of craft/storage/runtime/sessions

For whatever reason, even though  craft/storage/runtime/sessions has CHMOD 777, PHP was saving the session file with 644. When it tried to write to the same file again, it got and error and logged me out.

I also (unsuccessfully) tried giving PHP ownership of the folder, which should in theory fix the problem too.

 sudo chown -R www-data:www-data sessions
 chown: www-data: illegal group name


I am assuming it's a Vagrant/OSX thing.