One should, I suppose, tip the hat to “The Ring 2” simply for not being the same movie as the first one–the bane of many sequels. Unfortunately, the changes made by the filmmakers prove to have been very poorly conceived. To add to the distress, director Hideo Nakata, who made the original “Ringu” and its two successful Japanese sequels, stages the picture with such painful slowness that it practically dies on the vine. One can get away with this sort of deliberation–even profit from it–when the material you’re dealing with is genuinely creepy. Unfortunately, that’s not the case here; this “Ring” is strictly zircon, not diamond.

You’ll remember that original movie, directed by Gore Verbinski, for all its flaws had a clever premise–about a cursed video tape that doomed anybody who watched it to die in seven days (unless he made a copy and got some other poor soul to watch it, thereby dooming him instead). It’s actually a pretty ridiculous idea, and in reality the earlier picture made a hash of providing an explanation for the phenomenon–the tape was supposedly produced by the ghost of a girl angry with the world because her mother had killed her. But rather like the simple but brilliant hook of “A Nightmare on Elm Street” (a madman killing kids in their dreams), the “tag, you’re it” device worked for the duration of the movie, especially since at the time it was released, the ubiquitousness of VHS tapes meant that it was a threat everyone could relate to (just like drowsiness). But in the sequel, the entire tape business is pretty much jettisoned after the first reel (maybe because it was already sent up–however poorly–in “Scary Movie 3”), and the movie turns into a standard-issue possession flick, with the evil entity behind the tape going to absurd–indeed, seemingly endless–lengths to take control of Aidan (David Dorfman), the weird little boy from the initial “Ring” whose mother Rachel (Naomi Watts) uncovered the whole business the first time around. (The pair have moved to the isolated seaside community of Astoria, Washington, to flee the malignant spirit, but somehow it turns up there nonetheless: a high school kid named Jake is the first victim, and his death brings Rachel the unwelcome realization that she and Aidan are in danger again.) What’s the motivation behind the dead girl’s efforts? Why, she wants a real mommy, of course–the home she’d been once denied. And so in a curious fashion “The Ring 2” is supposed to be about the importance of family.

But as it winds up on screen it’s actually not about much more than special effects. Most of them involve water–mysterious floods in the living rooms where the tape takes its toll, bathtubs that overflow against the laws of gravity, and so on, presumably because the phantom girl was killed by being thrown into a well where her half-decomposed body remains even today. But others come entirely out of left field. There’s a lengthy sequence, for example, when a herd of deer attack the car Rachel and Aidan are in–presumably because he’s now been possessed and the animals can detect the evil in their midst. But the whole bit seems dragged in arbitrarily for immediate visual effect, as though in one of the script conferences somebody said, “Hey, I had a nightmare about deer, and it was really scary,” and the idea was abruptly cobbled into the draft because it would make a neat CGI opportunity. Certainly nothing more comes of it; one might expect dogs and cats to react in a similar fashion, but none are ever about to test the hypothesis.

That’s just one of the many plot threads left dangling in “The Ring 2.” Here, as in so many Japanese psychothrillers and American remakes like “The Grudge,” things just happen for shock effect, never integrated into an overall explanatory arc, however bizarre it might be. The ghost in both this movie (and to a lesser extent its predecessor) seems to be able to do anything it chooses, whenever and wherever it likes, so even as fundamental a piece of furniture as the cursed tape becomes unnecessary. In order to be genuinely frightening, a horror flick still needs some internal logical scheme–a set of rules it will play by. That’s what makes it fun. And by this second installment the “Ring” franchise has abandoned the ones it seemed originally to establish and that made it perversely enjoyable.

Still, “The Ring 2” might have generated more chills than snores if Nakata had directed it with a bit more zest. As it is the movie plods along, trying to create a brooding atmosphere of menace but instead engendering one of boredom. The picture ambles toward the two-hour point, which is way too long for this sort of genre piece. The cast naturally suffers. Watts can get by slowly sauntering around darkened rooms alone or calling out her boy’s name into empty hallways only so many times before the cliche has ceased to be amusing and become simply dull. And though Dorfman certainly has a spooky air about him (he’s sometimes vaguely reminiscent of Michael Dunn, the dwarf who played Dr. Loveless on the old “Wild Wild West” TV series), his relative blankness leaves a viewer less concerned about his fate that one ought to be. Simon Baker, as Rachel’s boss at the local newspaper, has little to do but appear concerned, and poor Sissy Spacek, wearing a hideous frightwig and looking as though she’d dusted her face with flour, does an embarrassing cameo as the ghost’s natural mother, an inmate in an asylum, as does Elizabeth Perkins as a psychiatrist who tries to help Adrian, to her grave distress. The movie does perk up momentarily when Gary Cole shows up as a high-pressure real estate salesman, but he leaves the scene far too quickly. Technical credits are fine, with suitably dark lensing by Gabriel Beristain and a supportive score from Henning Lohner and Martin Tillman, making use of Hans Zimmer’s original music for the first movie.

But the sad fact is that “The Ring 2” goes off on a wrong curve, and then doesn’t traverse it terribly well. The ultimate insult is that a 16-minute short produced for the new DVD issue of the first movie (and sent to critics on VHS tape as a publicity stunt) is scarier than the sequel. Done in a style reminiscent of “The Blair Witch Project,” it’s a prologue to “Ring 2,” showing how Jake (Ryan Merriman), the kid whose death sets off the plot of the picture, was induced to watch the tape in the first place and frantically tried to get somebody–anybody–to consent to view the copy he’d made and free him from the curse. It’s not a great piece, but at least it has some energy and edge–qualities sorely lacking in Nakata’s lumbering feature.

Maybe we can sic that herd of deer on it.