Before you add any AD intergration make sure the host name changer is working correctly.

If this is not AD will also fail.

Verify that the name is properly set via the webgui (the mac address for that pc is set to the name you want).

On ever restart of the pc the host checks in with the server only once to make sure it has the right name. If not it will restart, if it does it will ignore it.

You can speed this process up by going to services.msc ----> fog service ----> restart.

Do your testing that way. Once this is working correctly focus on AD... as others have mentioned make sure the password is encrypted using fogcrypt. Also some others have mentioned in the past that md5 packages were not installed correctly on their fog version (check the supplied links above).