A box given to Pandora by Zeus whose instructions that it must not be opened were ignored with disastrous consequences
{i} box opened by the first mortal woman which released all human ills into the world (Greek Mythology); any situation that creates more problems than existed beforehand
open a Pandora's box to do or start something that will cause a lot of other problems (Pandora woman in an ancient Greek story who opened a box and let all evils out into the world)