Pandora's box
Concise Oxford English Dictionary © 2008 Oxford University Press:
Pandora's box/panˈdɔːrəz/
▶noun a process that once begun generates many complicated problems.
– origin from Pandora in Greek mythology, who was sent to earth with a jar or box of evils and contrary to instructions opened it, letting out all the evils to infect the earth; hope alone remained.
'Pandora's box' also found in these Oxford entries:
