*Like the popular syndicated radio show that bears its name, Robert Altman’s new film “A Prairie Home Companion” occupies its own unique time bubble. Nostalgic for an idealized version of wry family entertainment that probably never quite existed, it embodies all that is strong in character about the Midwest, or at least what should be. The movie itself is typical Altman, an ensemble slice-of-life piece, but has the stamp of the radio show’s creator/host Garrison Keillor all over it.Beginning just before the fictional last broadcast of the long-running program, “A Prairie Home Companion” focuses mostly on the backstage goings-on at the Fitzgerald Theater in St. Paul, Minnesota. Even though the cast members and musicians all seem to know this will be their swan song, nobody is talking about it. The “show must go on” mentality serves as a safety net for Keillor, who plays GK with the same wistful nonchalance that he has become known for on the radio. Life comes and goes, and GK rolls with the changes, ending his last broadcast with no mention of the show’s demise, but in fact an announcement to see everyone back next week.Others, like singing sisters Yolanda and Rhonda Johnson (Meryl Streep and Lily Tomlin), prefer to acknowledge the end of long-running show that began back when there were four Johnson sisters in their act. Death casts a contemplative shadow over all the performers, and even Yolanda’s daughter Lola (Lindsay Lohan), the only character in the movie who actually dresses like its 2006, writes poems of teenage angst that all have to do with suicide. Perhaps partially due to Altman’s age (the recent Honorary Oscar winner was 80 during filming), the plaintive musings of “A Prairie Home Companion” take on a more stoic quality in this movie adaptation, particularly when dealing with the inevitability of death. Keillor penned the script from a story by him and Ken LaZebnik, and despite its sad moments, the film never devolves into a maudlin tearjerker. That old Midwestern resolve leaves its characters unforced and natural, free to keep on pluckin’.Despite its themes, there are plenty of moments of comic relief from singing cowboys Dusty and Lefty (Woody Harrelson and John C. Reilly), whose inoffensively “offensive” song about bad jokes is sure to be nominated for Best Original Song come Oscar time next year. The two have genuine chemistry, whether performing onstage or having rambling arguments with GK that threaten to derail the show’s live schedule. Saturday Night Live’s Maya Rudolph gives a subtle and terrific performace as the pregnant stage manager who struggles with GK’s incessant backstage storytelling (that mirrors his rambling onstage persona) and isn’t above feigning birth to get the performers’ attention. Sometimes it takes that amount of fortitude to keep the production on its feet. The fact that she is expecting and Yolanda’s daughter is present backstage during this final performance are characteristic reminders that life is a cycle, and that it never truly ends.Virginia Madsen saunters in and out of the wings, observing this snapshot in time in a luminous white trenchcoat. In the credits, she is listed as Dangerous Woman, the femme fatale for Kevin Kline’s bumbling Guy Noir (repositioned from Keillor’s radio show here as the theater’s head of security) to obsess over, although she holds a more mysterious sway over some members of the cast. She would fit better in a hard-boiled detective novel than Noir, who, despite his name, is more Inspector Clouseau than Philip Marlowe. There is an intruiging mystery involving Madsen and the Axeman from Texas (Tommy Lee Jones), but it mainly serves to highlight the characters and their diverging pasts rather than move the plot forward in a traditional sort of way.Having the big corporation from Texas buy up the thater and shut down the weekly homespun philosophies of “A Prairie Home Companion” is an obvious device, as are some of the radio show’s gags. Keillor is able to explore the same type of humor as the radio program, but Altman’s fluid camera adds some new depth to the behind-the-scenes funny business. What helps the movie stand out on its own is the resolution that its characters have in the face of bad news, as if their piece in the puzzle of life hasn’t been forged completely yet.