By Karla Petersen

CHULA VISTA - Her cardigan was a practical beige. Her long hair was neatly pulled back. Her glasses were probably smudge free. And after she leaped to her feet and greeted Stevie Nicks' Coors Amphitheatre entrance with an ear-splitting wolf whistle, the woman in the sensible clothes looked properly horrified.

"How did this happen?" you could hear her wondering as she sunk back into her seat. "What in the world came over me?"

Whatever it was, Nicks makes it happen to the best of us. When you find yourself thinking: "Ah, yes. Thunder does only happen when it's raining." and contemplating your first shawl purchase since 1975, you know some form of mind alteration has taken place. And the collective sigh that enveloped the sprawling amphitheater on Tuesday night was the sound of some 7,500 people succumbing to a spell that is more than 20 years old, and still as potent as ever.

As everyone from Bette Midler to Marilyn Manson could tell you, there is no particular magic in being weird. The trick is in making your eccentricities make sense. And for all her crystal-vision musings and witch-woman excesses, Nicks has always made a certain kind of sense.

Scrape off the glitter and newage goop, and you'll find an analytically inclined songwriter who has spent the last few decades grappling with the questions that bedevil even the cardigan wearers in the crowd. How do you juggle love and a career? Is it possible to age gracefully? What happens when your dreams come true, and they're full of nightmares?

By wrapping these tough emotional nuggets in layers of fairy-tale imagery, Nicks makes real life seductive enough for rock 'n' roll. And by tempering her star-child goofiness with earthy sincerity and affable charm, Nicks turned in a performance that felt real even if you had to strip off an awful lot of shawls to get the naked truth.

After spending the last year performing with the newly revitalized Fleetwood Mac, the 50-year-old Nicks was clearly thrilled to have the spotlight to herself. Touring to support "Enchanted," her new three-CD set of hits, B-sides and unreleased tracks, Nicks was free to sing all the songs she couldn't shoehorn into the Mac shows. And while her two-hour show was a pretty savvy mix of Fleetwood Mac hits, solo favorites and unexpected chestnuts, Nicks' magic wasn't all powerful all the time.

Following an enthusiastic (if sonically muffled) 30 minutes of blues and boogie-woogie from San Diego's A.J. Croce, Nicks opened with a set of songs that summed up her strengths and weaknesses in one neat swoop.

Draped in her usual black chiffon, Nicks started the show with "Outside the Rain," from her 1981 solo debut, "Belladonna."

Maybe it's only a dream / I don't want to feel that. Well it's one more link in the chain / I don't believe that. On the lyric sheet, it sounds kind of silly. But as Nicks tugged restlessly at the scarf tied to her microphone stand, she plumbed the song's psychodrama depths and came up with a convincing portrait of a woman doing her best to turn an impossible love into a sustaining relationship.

From there, the band moved seamlessly into "Dreams," and the show stumbled into its biggest pothole. As polished as it was, Nicks' nine-person backup band was not Fleetwood Mac. And as strong as they are, "Dreams," "Gold Dust Woman," and "Rhiannon" are not just Stevie Nicks' songs, they are Fleetwood Mac songs. And without Lindsey Buckingham's insinuating guitar or John McVie and Mick Fleetwood's empathetic rhythmic support, these Mac chestnuts sounded hollow and surprisingly bland. Nicks sang them with conviction, but they needed the Fleetwood Mac spark to turn glitter into something more lasting.

Nicks had better luck with her solo material, and with the exception of clunky renditions of the moody "Edge of Seventeen" and "Stand Back," so did the band. A wry rendition of "Enchanted" showed what happens when a star child tries to grow up, while stomping romps through "Whole Lotta Trouble" and Tom Petty's "I Need to Know" were as delightfully defiant as Nicks' trademark platform boots.

Throughout the evening, Nicks thanked the adoring crowd for their support, and if you had doubts about her sincerity, her tender version of "Has Anyone Ever Written Anything For You" whisked them all away. She may have her head in the clouds, but Nicks has never lost sight of the things that matter. That's her magic -- and it works.