When, despite headliners like Reese Witherspoon, Paul Rudd, and Jack Nicholson, your $120 million comedy drama opens in eighth place, reaps a paltry $7.6 million at the box office, and is on track to be 2010's biggest flop, it's time to ask a few questions. Just how did director James L. Brooks' How Do You Know manage to tank so badly? (Watch the trailer for How Do You Know.) Here, four theories:

1. Witherspoon has lost her following
Reese Witherspoon has been a "pretty solid audience grabber" for 10 years, says Monika Bartyzel at Cinematical, helping some decidedly mediocre romantic comedies make decent money. So "why not this time?" It's hardly as if rival films like Yogi Bear or Tron pulled away "hordes of Reese Witherspoon fanatics." The sad truth: "It simply seems as if her star is fading."

2. Poor marketing, worse title
The movie's marketing was too murky, says Jen Chaney at The Washington Post. "From the trailers and promos, it was hard to get a sense of what the multi-layered story was about. And that title: It's "a question that lacks a question mark and doesn't stick strongly in the memory." No wonder audiences didn't leap to answer it.

3. It was half-cooked
The "lackluster, muddled script" by Brooks (As Good as It Gets, Broadcast News) was partly to blame, says Anthony d'Allesandro at IndieWire. And it's entirely possible that "Brooks' tendency to edit late [in the process] precluded the studio from preventing a disaster." In any case, critics "loathed" it, and audiences who were polled on their way out of theaters agreed.

4. A-list stars don't make money
The big names in How Do You Know couldn't overcome this array of problems, says Ben Fritz at The Los Angeles Times. It's yet more proof, after the failure of Angelina Jolie and Johnny Depp to deliver box office receipts for The Tourist, that "star-driven" vehicles are "no longer working for Hollywood."