If user loses connection with SOI while editing a service the lock on the service could remain. Even if that user logs back into SOI, he can't edit the service because it's locked. If a user tries to delete the service, you would get a message:
"The following items could not be deleted: Error deleting model: attempt to create delete event with null entity. Please check the logs for detailed error description."
You can remove the lock by doing the following:
1. Go to the UI servers debug page:
http://<UI Server>:7070/sam/debug/
2. Select the Model Locks link on the left.
3. Now select the "Remove Action" for the problem service.