I've run into a problem with a new file server running 2012. It worked fine until last week when I started getting processor use alerts. It went to 100% and stayed there...turns out it was the lsass.exe process but I don't know what caused it. I eventually had to restart the server and it was ok for a week, now I'm seeing the same exact problem again. Nothing else is acting up, just that one service. I see very little results in my searches so I'm hoping someone here has seen the same problem.