Prevent Windows shutdown when nbackup is backuping database

I have script which is periodically running nbackup tool for database backup. I noticed that if Windows is restarted when nbackup is running, database ends up in "backup lock" state. Is there any possibility to force Windows to not kill nbackup process?

I noticed that if I run nbackup from WindowsForm application which in FormClosing event prevents Windows shut down, nbackup process finish successfully. But can I rely on observed behavior that processes are stopped/killed in order as they were started?