JACKSON SCRAMBLES

Exactly how paranoid Michael Jackson, 31, has become under the stress of fame probably none of us will ever know. But he definitely values his privacy.

A source in the electronic-surveillance field tells us that last Christmas Jackson purchased from a New York-based security firm a briefcase featuring a hidden tape recorder (for $900) and six Voice Safe telephone scramblers ($1,500). The briefcase can be used to secretly tape meetings, and the scramblers make it impossible to tape a conversation off a telephone line. However, in order for Voice Safe to work, it must be connected at both ends of the call.

The source had no idea why Jackson wanted the briefcase or with whom he was sharing his scramblers.

RING OF HORROR

Although boxer Evander Holyfield is considered the No. 1 contender for James "Buster" Douglas's heavyweight championship crown (former champ Mike Tyson is ranked No. 2), he's already working on a second career. Holyfield, 27, is the co-executive producer of Blood Salvage, a $2 million horror movie that will be released nationally in July. As a producer of the independent film, he offered script suggestions and made a cameo appearance.

Holyfield's movie is apparently so gory that the publicity-savvy boxer plans to send messages, via newspaper ads, to his two main rivals, Douglas and Tyson, offering to donate $10,000 to each man's favorite charity if they can watch Blood Salvage without turning away from the screen. Of course, if Holyfield gets beaten by Seamus McDonagh this Friday (June 1) at Trump Plaza in Atlantic City, he may find himself moving full-time into his second career a little sooner than he expected.

DOING JUST FINE, THANKS

Forget those stories you may have heard that have singer Billy Joel seeing another woman. Joel, 41, and his wife of five years, supermodel Christie Brinkley, 37, remain very much together. In fact they're together right now in Europe, where the international leg of his Storm Front concert tour continues through early June.

"Our marriage is very solid. It always has been," says Joel from London. "I guess when celebrity news is slow, the press starts cooking up the old Billy-Christie split story. The most aggravating thing about it is that there is a child involved here [daughter Alexa Ray, 4]. say enough is enough. Leave us alone."

MUSICAL CHAIRS

When Madonna performed recently in Los Angeles, her agents at the powerful Creative Artists Agency made free tickets to her concerts available to certain star clients and other assorted Hollywood celebrities.

No doubt CAA clients Rob Reiner, 43, and his ex-wife, Penny Marshall, 47, felt good being on CAA's free ticket list, but neither could have anticipated that their own agency would seat them next to each other at the show. After all, the TV stars turned movie directors have been splitsville since 1979, after nearly a decade of marriage.

So when Reiner arrived at the Sports Arena, how did he handle the touchy seating situation? He swapped seats with another concertgoer and saved both Marshall and himself from a potentially uncomfortable proximity.