Cookie Issues with Main Domain and Subdomains

Good evening folks, I hope this won't be too much of a burden in
asking but I seem to be scratching a wooden post down to mere pulp
right now.

I own the following main domain:

nukecops.com

From that I have created several subdomains, examples include:

phpnuke.nukecops.com
bbtonuke.nukecops.com
beta.nukecops.com
nukemods.nukecops.com

These are PHP-Nuke portals that are powered by Apache on a Redhat OS.
Here is my issue...

When logging into the /forums.html link from 'nukecops.com', one sees
the forum indexes and is able to drill down to any forum thread
successfully.

Now while logged into 'nukecops.com', if one were to browse
'/forums.html' at any of the above subdomains like
'nukemods.nukecops.com/forums.html', one would not see the forum index
at all. Nor would one be able to drill down to any threads because
they simply vanished.

However, let us backtrack a bit. If one were to never log into
'nukecops.com' one may then freely browse the forum index at
nukemods.nukecops.com (or any of the other subdomains) while drilling
down to any of their threads.

Now the settings.

Each domain/subdomain has the same name set for its cookie_domain
within the phpbb forums configuration, ie:

nukemods.nukecops.com = nukemods.nukecops.com

Within my apache configuration for this subdomain is found this:

<VirtualHost 66.227.19.157>
ServerName nukemods.nukecops.com
ServerAlias www.nukemods.nukecops.com
ServerAdmin xxx
DocumentRoot yyy
<IfModule mod_expires.c>
<Directory yyy>
ExpiresActive On
ExpiresByType image/gif "access plus 1 hour"
ExpiresByType image/jpeg "access plus 1 hour"
</Directory>
<FilesMatch "\.jpg$">
ExpiresActive On
ExpiresDefault A3600
</FilesMatch>
<Directory yyy>
AllowOverride All
</Directory>
</VirtualHost>


Here are my settings for 'nukecops.com':

<VirtualHost 66.227.19.157>
ServerName www.nukecops.com
ServerAlias nukecops.com www.nukecops.com
ServerAlias nukecops.net www.nukecops.net
ServerAlias googletap.com *.googletap.com
ScriptAlias /cgi-bin/ "111"
ServerAdmin xxx
DocumentRoot 222
<IfModule mod_expires.c>
<Directory 222>
ExpiresActive On
ExpiresByType image/gif "access plus 1 hour"
ExpiresByType image/jpeg "access plus 1 hour"
</Directory>
<FilesMatch "\.jpg$">
ExpiresActive On
ExpiresDefault A3600
</FilesMatch>
</IfModule>
</VirtualHost>

(I replaced locations with letters or numbers, same for emails.)

Any suggestions or recommendations to optimize this so that one may
log into 'nukecops.com', browse its forums/threads with ease while
also being able to visit the other subdomains to browse those
forums/threads with success?

Thanks for your time in advance.

Paul