[Sam Bauers]

Does your site always have “www” in front of it?

In any case, try changing the COOKIE_DOMAIN in WordPress like so (note the dot in front of the domain):

define('COOKIE_DOMAIN', '.site.com');

Also enter this value in bb-config on the bbPress side:

$bb->cookiedomain = '.site.com';

Doing this will log you out, but you should be able to just log back in.