I can log in to the CMC with AD authentication just fine as can several others but we have a few users with the same AD setup and my own and they can not login. I also had one user who coudl log in fine at 3 and then an hour later they could not.
And ideas on where to troubleshoot. It seems that everything I find is related to setting up SSO and new installation. But we have been up and running without any problems for some time.