Is it possible that the box represents a womb? I think that makes a lot of sense, because it's a cavity with an opening, and things come out of it (that were never seen on earth before). The myth also is a commentary on gender, because it's a woman who releases evil to the world, and Pandora's husband is at fault only because he is stupid enough to marry her.
It is 100% supportable that the "box" represents the womb in Hesiod's version of the myth from his Theogony. In brief:
In the Theogony, Hesiod never mentions any vessel save Pandora herself.
Pandora is cast as the mother of the "race of women" who were created to vex men (i.e. they are the source of evil named by Hesiod in the Theogony.)
In other versions of the myth, no "box" is mentioned, but instead a pithou meaning "jar" for wine or oil. (If wine, it could represent blood, and oil is a lubricant.)
The idea of woman as vessel is a major point in Apollo's notorious arguments in Orestes' defense in The Eumenides, demonstrating the existence of this concept in Ancient Greek thought.
You can find a more detailed explanation of this element of the myth here, as well as a discussion of the possible meaning in Aesop and Hesiod.
I don't think that the point of the myth lies to the fact that it was Pandora that openned the box, neither that the box necessarily symbolizes the womb. It could have been her husband, Epimetheus, that oppened it, and it wouldn't matter, the result would be the same. What matters is that Zeus knew all along that the box would be openned. The box was given to the couple as their wedding gift by Zeus, and he wanted to punish humanity this way, because humanity accepted the gift of the Holy Flame stolen by Prometheus. That made the humans more powerful than they were, and some of them became greedy and invaded Olympus to overthrow the gods, and become rulers in their place. Zeus zapped those who even tried to climb Olympus with lighnings, and to take revenge he thought of that trick with the box.
So basically the main point of the story is that accepting stolen goods is bad.
Note that Pandora's husband, Epimetheus is NOT a man. He is a Titan. Humanity prior to Pandora existed as beings that had no sexes and were given birth by Earth, literaly (According to the myth) sprouting out of soil like plants do. Thus women through Pandora is the oldest sex of the two. This is not something explicitly written, but one is lead to that conclusion one he realizes that the first humans didn't had a gender / sex and had no sex.
I do not interpret the tale of Pandora as the recounting of an actual event; no matter how modified or adapted. Instead, I read this as a "Test:" A test of the honour or obedience of a student or underling to the specific instructions of a "teacher," deity, spiritual leader, or other superior. The accounts of gods or holy persons almost invariably contain such "tests:" (This is even found in the Star Wars sagas!) The detailed "histories" of the persons being tested vary widely, but usually devolve upon specious "explanations" as to why the student had felt justified in being disobedient. There is always some reason given as to why the "student," the subject of the tale, had felt that disobedience was appropriate. That is precisely why these tales are so common! Obedience is vital if one is to learn and grow! The god, spiritual leader, shaman, or "superior" in general is daily sharing valuable information with the student. This knowledge constantly builds upon itself, and can be miss-used, if the student is not completely trustworthy. That is why there are so many "tests:" The superior must be satisfied that the student will not disobey--- no matter how much "justification" is seemingly presented. Following the instructions of one's superior(s) completely and implicitly is absolutely vital, in the case of lower-ranking students. "Situational Ethics," or obeying one's superior when-ever one imagines it is justified, has no place in metaphysical, spiritual or "holy" instruction! I had been raised to always obey my parents, and elders: When I came to study under a particular shaman, I was curious when he presented to me a "Pandora" puzzle almost daily. I always chose to obey the scenario suggested by the god, wizard, etc. in the tale. I was at last asked why I did as the "elder" had suggested-- did I not have any opinions of my own? Replying, I said that I had a plethora of opinions, but because I had not been receiving instruction very long, I had little knowledge, and less experience. Until I had more knowledge and experience, I wanted to learn from the experience of someone wiser, I'd concluded. Shortly after, I found that my instruction was devoted more to "arcane knowledge" and less to remedial topics. I had evidently passed my shaman's tests in "Honour" and "Trustworthiness." I did not include this to brag in any way, but rather, to illustrate how an instructor will often test, test, and retest students in "Pandora Matters," until satisfied with the true character and honesty of the subordinate. I have done this with students of my own: Two had proven to be persons of honour. Others, with character traits like cruelty, laziness, or a fondness for "situational ethics," were asked to leave.