Operator does not know how they locked up the register. To solve this,turn the power switch off,turn key to program position. While holding down the subtotal key power the machine back on while you continue to hold the subtotal key. Register will print initial clear. Turn key back to register position. Register will say closed. Enter 1 and press the clerk key. This will unlock your register andd you can continue to use the register. You only loose the current transition you were in when the register locked up.