When it comes to casting demons from the bodies of innocent youngsters, why should Catholics have all the fun? In William Friedkin's "The Exorcist," Max Von Sydow's Father Merrin stepped right up to the plate when Linda Blair began doing some pretty nasty things with a crucifix. The problem is a little less straightforward -- and less overtly symbolic -- in "The Possession": A young girl starts acting strangely after she picks up an unassumingly sinister-looking tchotchke at a yard sale. The item in question is a Dibbuk Box -- according to Jewish folklore, a cask containing a malevolent spirit that's just waiting for the right human host to pour itself into -- and believe you me, only a shmendrik would try to open it. Or, perhaps, a curious little girl. In "The Possession" that little girl, Em (Natasha Calis) is still adjusting to the breakup of her parents' marriage; Clyde (Jeffrey Dean Morgan) and Stephanie (Kyra Sedgwick) are themselves still trying to work out the particulars of their divorce, and the atmosphere of unrest is just the sort of place for a restless demon to take root. When Em and her sister, Hannah (Madison Davenport), go to visit their dad on the weekend, the spanking-new house he's just bought is ghost-free -- in this case, Em brings the ghost with her, inside that box. It's a dark wooden thing adorned with mystical symbols, and Clyde can't open it, not even with all the manly dad tools he has lying