The error reported in the title is, "403 Forbidden", but the page also reports, "Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request."
In settings.php (under alpha only) I've uncommented and played around with the following line:
$base_url = 'http://alpha.paladolphin.com';
I'm currently using the same database, but will create a duplicate once I solve simply bring up the alpha site.
I have created the sub-domain alpha.paladolphin.com and pointed it toward /public_html/alpha. The www.paladolphin.com resides in /public_html.
I've created a unique filename http://alpha.paladolphin.com/imgs/SpringSnow_f.jpg that doesn't exist any where else but under the alpha folder to prove that the new sub-domain works.
I've also searched the Drupal knowledge base for a similar problem, but they all are way more complicated than this baby step I'm trying to achieve.
The sole purpose of this alpha. website is to allow the www. to work live while I experiment with future configuration on the alpha. site. Once I get a configuration working on alpha., I'll migrate it to www. and continue experimenting with alpha.
Any help would be greatly appreciated!