Sandra Cortez went to buy a new car on her lunch break, and about an hour later, the Denver dealership staff was threatening to call the FBI to haul her away as a suspected terrorist.

The dealership's routine check of Cortez's credit report turned up something unusual on that day in 2005. It was an alert indicating that the woman was on a government list of suspected terrorists, international drug traffickers and others associated with weapons of mass destruction.

Cortez, now 68, was really just an accountant who wanted a new silver Subaru to better navigate the mountain roads she traveled to reach her favorite hiking trails.

The credit report Cortez had seen long before she walked into the dealership was clean. She had excellent credit, and she had no inkling that she was linked to a Colombian woman with a similar name wanted for drug trafficking. But like so many other consumers, Cortez didn't realize that the credit reports issued to businesses are not the same as those given to consumers.

The ordeal engulfed the grandmother for the next five years. Her many attempts to fix the problem with TransUnion and the federal government on her own all failed. Cortez pleaded with the credit-reporting agency to correct her credit history but received no help.

She eventually hired Jim Francis, a consumer-law attorney in Philadelphia, and sued TransUnion. Cortez endured a grueling legal battle that included a trial and years of appeals. She originally was awarded $750,000 by a jury, but that later was reduced to $150,000. And the government took about a third of it in taxes.

Officials for TransUnion's lobbying group, which speaks for the company on all matters, declined to comment on the case. Current owners of what was then the John Elway Subaru dealership were unfamiliar with the case and declined to comment.

But it was that day in the auto showroom that Cortez realized how powerless Americans are to defend themselves against significant flaws in the credit-reporting system.

"I thought I would be driving my new car back to work after lunch," said Cortez, who is now retired and living in La Mesa, Calif. "I couldn't imagine what would happen next."

Here's how it unfolded on March 31, 2005:

1 p.m. — Cortez turns into the Subaru dealership parking lot in her old, red Ford Taurus. A friendly saleswoman greets Cortez and tells her the new silver Subaru Forester will be ready shortly. They just need to go through the financing process. Cortez is expecting a good interest rate on the $18,000 Suburu Forester she is financing and picking up, because she had checked a week earlier and her credit score was 761.

2 p.m. — An hour passes as Cortez waits in the finance manager's office. He returns with only a stern look and a series of strange questions:

"Were you born in the United States? Have you always lived in the U.S.? When is the last time you left the country?" the manager asks.

The manager tells Cortez that the TransUnion credit report indicates that she is on the U.S. Treasury Department's Office of Foreign Assets Control list, which tracks specific individuals or regimes suspected of being terrorists. TransUnion's "OFAC Advisor" service had mixed Cortez with a Sandra Cortes Quintera. Businesses use such services because the Patriot Act, passed shortly after the Sept. 11 attack in 2001, prevents lenders from loaning money to anyone suspected of being affiliated with terrorists.

"I am not that woman," Cortez pleads to the manager. "I have my credit report, and there is nothing like that on it."

2:10 p.m. — The finance manager tells Cortez that they are calling the FBI if her name matches that OFAC list.

3 p.m. — Cortez sits alone in the sterile office and waits for FBI agents. She expects them to burst through the lobby doors with guns drawn. She trembles and imagines what it would be like to be handcuffed and taken away in view of other customers and the sales staff.

3:30 p.m. — People are looking into the glass-windowed office where Cortez is sitting. Word has spread around the dealership that they may have caught a terrorist. Cortez tells the finance manager that she is hungry and is feeling lightheaded, but he asks her to stay a little longer. The dealership has possession of her Ford keys.

4 p.m. — Cortez is given her car keys by a front-desk employee, but the finance manager asks her to wait a little longer. He then says again that they are going to call the FBI. Cortez sits back down in the dealership lobby and again waits for federal agents to arrive. She could leave, she thinks, but she doesn't want them to think she has reason to run.

5:30 p.m. — Cortez is hungry, exhausted and afraid. But she thinks that if the FBI really wants her, agents can find her could just as easily pick her up at home. Cortez finally drives away from the dealership in her old Ford Taurus.

6 p.m. — Upon arriving at home, she immediately calls her daughter and tells her of the ordeal. She is still convinced that she will be arrested at any minute and tells her daughter that she might need legal help.

"They won't believe me," she says. "They just won't believe me. Everyone there thinks I'm a terrorist."

6:45 p.m. — Cortez calls the dealership and is transferred to its top manager.

"We think there has been a mistake," he says. "We would like to apologize."

7:15 p.m. — Cortez arrives back at the dealership. She's now treated like a VIP. Everyone is apologizing, offering her $100 in free gas and dinner for her and her family wherever they want to go. Cortez feels as though she was kept hostage for the day, but even so, she just wants her new car. And the only thing Cortez asks them to give her throw into the deal is a copy of the credit report they received from TransUnion. Cortez isn't sure if they ever really called the FBI.

She finally got the new car, but a five-year struggle to clear her name had just begun.

Cortez is still driving her 2005 Subaru — and still stinging from the experience of buying it.

"Most people think if you pay your bills on time, you will be OK in the credit world," she said. "But that's not how it always works. And sometimes, the mistakes can be paralyzing."