My Z series notebook (VPCZ21C5E to be specific) has an odd intermittent fault which I have now experienced 3 times in its 2 months of use.

1. Plugged into charger or docking station, working OK, battery fully charged.

2. Turn completely off, unplug.

3. Next day notebook will not turn on stand-alone i.e. when not plugged into charger.

4. Simply removing the battery and re-inserting it fixes the problem, will immediately boot on battery power without any apparent issues.

What can stop a nearly-new Z series notebook from starting from cold (not sleep or hibernate) when (a) the battery is fully charged (b) the notebook is otherwise fully functional and appears to have no (other) faults?