Logging into admincp redirects to server name?
 

I'm having a hard time figuring this one out. I've researched numerous threads that troubleshoot cookie problems, blank page problems, etc, but have not found out the root cause of this issue.

Issue:

My site is (for example) http://forums.mydomain.com. I can log into the site just fine. I click on the admin link, and I get the admin login prompt on on http://forums.mydomain.com/admincp/index.php . Now at this point, I login to the admin console and I see the "Thank you for logging in" message.

The problem is that it doesnt give me the admin console at this point. In the lower left corner of the browser (IE) I see a message that it is trying to connect to http://MyServername/admincp/index.php and then it ends up leaving me with a blank page and http://forums.mydomain.com/login.php?do=login in the URL/Address field.

Now at this point, I am logged in and have a proper cookie stored. Even though the site didnt leave me logged in at the admin console, I can retype in the proper url to the admincp and use the admin console as intended...

What I am really confused about is why the site would be looking for the admincp path at http://myservername rather than http://forums.mydomain.com.


History:

I've had this problem since I recently moved my test site from my development server to our production server. The original site had a few mods as well as VB Advanced installed. I went through many torouble-shooting efforts including all the settings defined in the blank pages document as well as the tools.php resets... Finally, I simply created a brand new vanilla site with freshly uploaded "stock" files and a new mySql database and I still have the issue.

VB version is 3.8.4.
PHP version is 5.2.10.
MySQL is 5.1.37.


Any suggestions would be greatly appreciated.