It seems that the affected models are from May 2010 to January 2012 and apparently a defective component in their power supply can cause the device to overheat and pose a fire hazard. So far according to Lenovo, there have been two customer reports which have resulted in damage to their computers.
So is your Lenovo M90z or M70z affected? Well, Lenovo has stated that not all models in that timeframe are affected and that the recall is voluntary, but if you’d rather not take that risk, pop on over to Lenovo’s website for more information or to check if your model is one of the affected units.