I recently made some layout changes, over several days, to the master site and all went well. Today I tried to login to the administration area of the master site to add a new article and I now get a loop. There are not errors, nothing...just continues to ask for the credentials. I have tried Chrome, Firefox and IE8 with no success. I can log into the the slave site admin with the same credentials with out any issues.

Please advise as we need to add now details.

Regards,

John

If you use Joomla 1.5 and that you shared the users of the master with a slave site, it is possible that you can not login if the domain name does not correspond to the websites that you used to manage the slave site definition.
In Joomla 1.5 and sharing of the users, the session cookie domain for the master website is computed based the domain name that you used to manage the slave site.

So if you have installed JMS in a slave site (that is not recommended) and that you have managed the slave site definition from a slave site the you may have been forbidden to access your master.

On Joomla 2.5, this could be due to the value that you would setup in the "global configuraion" with the "cookie domain" field.

If you want to temporarly disable JMS it is possible to create a file or a folder with the name "multisites_disable.php" into the /includes directory

When /include/multisites_disable.php exists, this disable the JMS super switch and should give you the access. Becarefull that in this case, all the slave site will display the master as JMS is no more actif.