Fleetwood Mac is back on record, and may be back live as well.The band, whose “Don’t Stop” was the unofficial theme for Bill Clinton’s campaign, may reunite key members of its hit-making lineup — including estranged guitarist Lindsey Buckingham — for a performance at Clinton’s inaugural ball in January, according to a rumor making the rounds. And even though vocalists Christine McVie and Stevie Nicks refuse to tour, Fleetwood Mac is still a studio entity, spawning several new tracks for its new Warner Bros. boxed set, “25 Years: The Chain.” The four CD-set covers the Mac’s evolution from the days when drummer Mick Fleetwood and bassist John McVie spun off from John Mayall’s Bluesbreakers through the era when the Mac were pop’s kings ‘n queens, spawning top-10 hits “Go Your Own Way,”"Dreams,” and “You Make Loving Fun.” However, the set’s downfall is its seemingly random order: this is possibly the first box set that bears no resemblance to the careful chronological efforts that usually mark retrospectives. Including all but one of the band’s top-20 singles (only “Hold Me” from 1982 is omitted), the selections flow in no particular order from every incarnation of the group, which went from a blues band (featuring Peter Green and Jeremy Spencer), morphing slightly with the addition of guitarist Danny Kirwan, then moving into its pop phase beginning with contributions from singer/songwriter Bob Welch before arriving at the Nicks/Buckingham-led stadium tour era. Four new tracks are offered as an incentive for longtime fans to repurchase the music, including “Paper Doll,” a recording that contains every group member since 1975. Other cuts of interest include new track “Love Shines,” and an unreleased Danny Kirwan song, “Trinity.” As is the case with all boxes, you can’t please everyone. For this listener, the lack of songs from “Then Play On” and “Future Games” (particularly the haunting “Woman of a Thousand Years,” which pre-dated the dreaminess of the Cocteau Twins by 15 years) is criminal.