I DON’T CUSTOMARILY dispense unsolicited advice, but in view of the vicissitudes facing Arnold Schwarzenegger this week, I’m tempted to make an exception. Now one might well ask, does anyone who makes $ 15 million a picture really need advice? Probably not, but even Arnold can stumble now and then. Hence the following:

MEMO TO: Arnold Schwarzenegger

FROM: Peter Bart

SUBJECT: Image Whiplash

I’ve been thinking of you this week, Arnold, wondering whether you were falling victim to that ailment known as “Image Whiplash.” This is the condition that occurs when, for no apparent reason, everything that appears in the press about you changes overnight from white to black, when reporters who on Monday were fawning are suddenly frowning on Tuesday. Arnold the Magnificent instantly becomes Arnold the Mendacious.

Knowing how seriously you take your career, I can imagine you sitting there, marshaling your advisers, feverishly analyzing the cause of the flip-flop. Hence I thought I might chime in.

First, some strategic observations. The anti-Arnold missiles have been fired from all directions. The New York Daily News depicts you as uncharitable. The Los Angeles Times suggests you cater only to reporters who ask creampuff questions and who, like David Sheehan, are willingly “Schwarzeneggered.” USA Today headlines, “Schwarzenegger’s star dimming …” and asks whether Arnold “can beat the bad vibes.”

Why the sudden onslaught? One reason is simply that the press enjoys being fickle — it’s an expression of power. “There’s a gravitational law that goes beyond Newton,” theorizes one Hollywood philosopher, Sylvester Stallone. “No one stays on top. There has to be a fall.” Stallone should know. He’s been down; his new film, “Cliffhanger,” may pull him up.

But let’s be honest, Arnold: Part of the problem is of your own making. In your exuberance at achieving stardom, you’ve managed to develop some serious syndromes:

The Madonna Syndrome, otherwise known as Hyper-hype: It’s one thing to sell your wares, Arnold, but at the preview of “Last Action Hero,” did you really have to say, “I’ve turned out another great movie and everyone seems to love it and the critics have already said that it’s a great summer hit”? Chill out, Arnold — just because they gave you executive producer credit doesn’t mean you have to sound like you’re selling used cars.

THE BILL CLINTON SYNDROME, otherwise known as overexposure: You don’t need to be everywhere, over-explaining everything, Arnold. In the old days of the studio system, the superstars were remote figures — almost amorphous. By contrast, you’re positively ubiquitous. It’s understandable that you want to pitch “Last Action Hero,” but how many Planet Hollywoods can you open in one year? Most stars do an occasional magazine cover, but the newsstands these days present a sea of Schwarzenegger. You’ve done three GQ covers alone in the past six years!

The Mickey Rourke Syndrome, otherwise known as taking the press for granted: It’s fine to make yourself available for interviews, Arnold, but it’s also gauche to boast about your PR productivity. At a huge dinner at Cannes last month, you announced with great pleasure that you had given more than 60 press interviews that day and had honed your answers so efficiently that the average interview took under three minutes. Now, Arnold, we’re all gratified that you talk so fast, but a reporter doesn’t want to be thought of as a Volkswagen on an assembly line. You’re supposed to tell an interviewer how clever he is, not how quickly he can be processed.

Now in saying all this, I don’t want to fall into yet another syndrome — namely, becoming mindlessly overcritical.

You deserve high marks in a number of areas, Arnold, and I want to be upfront about these. In a business where rudeness is venerated, you are meticulously courteous. You stand behind your work. You take a keen interest in the world around you, although your politics make Charlton Heston seem like a ’60s pinko.

You understand more about the specifics of distribution and dealmaking than any other top star I know, with the possible exception of Warren Beatty. Again, the difference is that Beatty shrewdly masks his knowledge while you flaunt it. Ask Beatty about the definition of adjusted gross in his newest deal, and he’ll start talking about Jack Nicholson’s art collection. By contrast, you sometimes sound like you’re preparing your doctoral dissertation in film finance at Harvard Business School.

Again, there’s a lesson to be learned from the past, Arnold.

WHEN STARS OF A PREVIOUS GENERATION like Steve McQueen or Robert Mitchum suffered image whiplash after the press turned on them, their mentors gave them some sound advice. Both cautiously withdrew from the fray. Both also mastered a type of StarSpeak — a marvelously arcane rhetoric that was essentially incomprehensible to a normal human being. Hence, on the rare occasion that they granted interviews, a reporter would listen carefully, then go home and stare at his notes with total helplessness. What they had transcribed was, in fact, a form of gibberish: The words themselves made sense, but, assembled into sentences, they made positively no sense at all. The Hedda Hoppers of that era would thus take pity and invent their own felicitous responses.

Arnold, perhaps you should take a lesson in StarSpeak. Forget the bravado, the hard-sell aphorisms, the self-hype. Forget about Planet Hollywood and all your other adventures in commerce. Cool down. Relax.

All of a sudden everyone will forget you’re the bad guy of the moment and start loving you again.