On Sept. 25 Harrison Ford was due to receive a Media Spotlight Award from Amnesty International USA for his work on behalf of Tibet and the environment. Last year Ford and his wife, Melissa Mathison, also a champion of the Tibetan cause, had cochaired the $250-a-plate event. But on this night the superstar sauntered up the red carpet at Manhattan's Chelsea Piers without Mathison, who turned up later unescorted to sit with her husband. All of which struck at least one event planner as decidedly "odd."

As well it might have. For the past 17 years the marriage of Ford, 58, and Mathison, 50, has been considered one of the most solid -- and envied -- in the relationship high-risk zone that is Hollywood. But on Nov. 7 the pair issued a statement announcing that they had, for now at least, separated. "We have been living apart for the past month," the statement read. "We sincerely hope that we can work out our differences."

So do friends of the couple's, who were floored by the news. "It's a total surprise," says Mace Neufeld, a Ford pal for more than two decades who has produced several of his films, including 1992's Patriot Games, which have made the actor the $25 million-a-movie star he is today. "They both worked so hard to keep their marriage and family private and non-Hollywood." Indeed, Ford and Mathison, who have two children, Malcolm, 13, and Georgia, 10, always seemed "an extraordinarily devoted couple," says Warren Adler, whose book Random Hearts was made into a 1999 movie starring Ford and Kristin Scott Thomas. "Their whole lives are wrapped up around their children."

According to Patricia McQueeney, Ford's manager of 30 years, the announcement of the split was triggered by "false and inaccurate media reports that have recently appeared in the tabloid press." Those reports have Ford in a Manhattan nightclub chatting closely -- and taking a hansom cab ride through Central Park -- with 30-year-old Lara Flynn Boyle , star of ABC's The Practice, whose yearlong relationship with Jack Nicholson, 63, seems to have fizzled this fall. Boyle's representatives had no comment, and McQueeney denies any connection between the nightclub chat and Ford's marital woes. "There is absolutely no third party involved," she says. Declining to elaborate on any specifics, McQueeney said Ford and Mathison are "just having their differences and are taking a break from one another. This whole thing with Lara Flynn Boyle is ludicrous. Harrison wouldn't be caught dead in a hansom cab."