What do you mean by having "AMT Enabled"? did you go through a full setup & config process (using either AMT Director from DTK, or SCS, or ...)? this process is needed only for the AMT Enterprise mode, not for Small Business... Also even when provisioning properly you should explicitly set WebUI enabled for the Enterprise mode.
Check for the different options available on your prefered Setup & Config server.
Hope that helps
Basically WebUI authentication should work with admin/XXXXXXXX as you set in MEBx.
I recommand you to go through the following checklist to be sure yourSMB/Enterprise configuration is completed correctly: http://softwareblogs.intel.com/2008/01/28/tips-tricks-for-setting-up-accessing-an-intel-amt-client/
For Enterprise mode, you need to use either SCS or Manageability DTK for provisioning the system. Please refer to this blog for various tools that can be used for Enterprise Provisioning.
I went through your questions again and was wondering what would you want to do here - Are you confused between SMB and Enterprise mode or are you trying to decide between the two? If so, the quick start guide will give you guidelines on this.
If you have decided on Enterprise mode, and would like to provision your system accordingly, you have to set it up in the Bios and then provision it using Manageability Director or SCS. I would like to know what are the settings you have done for Enterprise mode kin the Bios. The Strat Here guide that i mentioned earlier will help you to get started and properly configure the Bios settings.
Both the links Sree posted previously will help you with the differences between SMB and Enterprise mode. But to sum up, setting enterprise mode does not fully configure AMT, it needs to be enabled by sending a hello packet to a Configuration server and get a response back. You can obtain the Intel AMT Setup and Configurtion Server from here: http://software.intel.com/en-us/articles/download-the-latest-version-of-intel-amt-setup-and-configur..., as well as documentation on how to use it and a technical overview.Setting up SCS issome additional work above what is required for SMB mode.
If you want to use Enterprise mode, I'd highly recommend the previous two documents Sree linked so you can evaluate the differences. If you just are experimenting with AMT, I'd recommend using SMB mode.
When you change to Enterprise Mode in the BIOS, you are actually not completing the whole setup that Enterprise Mode expects. You will need to then go through the steps required by either the AMT ManageabilityDirector or the SCS in order to finish the provisioning. Once you do, you will be able to access the Web UI through https and port 16993, instead of the SMB port which is 16992. I suggest that you start with the Director as it is much easier to use.
If you have not already done so, please go to the Manageability DTK Download page and take a look at some of the reference links. The one called "Using Manageability Director Tool to configure TSL" may be of interest.
Are you running the Director as "Administrator?" I think that is what Javier is asking. Also, did you try doing the things that folks have suggested in your other post?