I have just spent the day trying to understand and work-around this error:
Error: objects/User.object(User):Entity cannot be untracked.
that (since this morning) comes up when I deploy our application using Ant and causes the deployment process to abort.
I could find nothing helpful on Developer Force or via Google. No one has commented on my Developer Force post. I have no access to additional log files. So I have created a support case that in two working days time will reach the top of the support queue and sometime later may get escalated to an appropriate person. Pity about an upcoming deadline we have.
So right now I am dreaming of past days working with open source products with active communities and the option of downloading the source and finding out exactly what the cryptic error message means when all else fails. While that did not necessarily make it easy to fix a problem, at least it kept the resolution of the problem in the hands of the person for whom it was priority #1 – me.