Vaughn Munnin if referring to droid ultra having a problem with shutting down and rebooting on its own with no warning. I know this because mine does it, at least once a day, so does my son's, and my wife's. And if you Google the problem, it seems there are lots of people with Motorola droids having the same problem.
So, just responding to a persons question with " what does "" keeps restarting mean"" does not help with her problem. If you are going to respond to a question, at least try to answer it.
As for the problem with the droid ultra, I don't know what is causing it, but Motorola has said the phone is responding to an "unspecified error" in the OS. Unfortunately, they don't tell you what the error is, because they don't know how to fix the error. Other people have said it's a battery issue, but the battery is nonremoveable battery, so other than having a bad connection, I can't see how it could be a battery problem.
I am trying to resolve this issue, because other than this the droid is an excellent phone.