I have an xp pool or machines. When user shuts down the machine, the vm powers off. But in View manager i has it set at
ensure vm is always powered on.
Pool setting has an option for what to do after the session is closed: if you choose alway power-on this mean that the VM remain powered-on, but it does not mean that it will prevent to manually power-off the VM.
To be sure that VM are powered-on you must use another pool setting, where you specify how many VM must be always available.