Alicia Istanbul woke up one recent Wednesday to find herself locked out of the Facebook account she opened in 2007, one Facebook suddenly deemed fake.

The stay-at-home mom was cut off not only from her 330 friends, including many she had no other way of contacting, but also from the pages she had set up for the jewelry design business she runs from her Atlanta-area home.

Although Istanbul understands why Facebook insists on having real people behind real names for every account, she wonders why the online hangout didn't simply ask before acting.

"They should at least give you a warning, or at least give you the benefit of the doubt," she said. "I was on it all day. I had built my entire social network around it."

Facebook's effort to purge its site of fake accounts, in the process knocking out some real people with unusual names, marks yet another challenge for the 5-year-old social network.

As Facebook becomes a bigger part of the lives of its more than 200 million users, the Palo Alto, California-based company is finding that the huge diversity and the vast size of its audience are making it increasingly difficult to enforce rules it set when its membership was smaller and more homogenous.

Having grown from a closed network available only to college students to a global social hub used by multiple generations, Facebook has worked over the years to shape its guidelines and features to fit its changing audience. But requiring people to sign up under their real name is part of what makes Facebook Facebook.

To make sure people can't set up accounts with fake names, the site has a long, constantly updated "blacklist" of names that people can't use.

Those could either be ones that sound fake, like Batman, or names tied to current events, like Susan Boyle. While there are dozens of Susan Boyles on Facebook already, people who tried to sign up with that name after the 47-year-old woman became an unlikely singing sensation had more difficulty doing so.

Facebook spokesman Barry Schnitt acknowledged that Facebook does make mistakes on occasion, and he apologized for "any inconvenience." But he said situations like Istanbul's are very rare, and most accounts that are disabled for being fake really are.

"The vast, vast, vast majority of people we disable we never hear from again," he said. Because the exceptions are so rare, he said, prior notification is "not something we are doing right now."

Facebook is available in more than 40 languages - and growing - and its user base is larger than Brazil's population.

But financially it is still a startup.

Although the Internet research firm eMarketer estimates that Facebook generated about US$210 million in U.S. advertising revenue last year, that's well below the US$585 million estimated for the News Corp.-owned rival, MySpace.

Facebook is still looking for ways to become self-sustaining and reduce its reliance on outside investors. In 2007, Microsoft Corp. bought a 1.6 percent stake in the company for US$240 million, though Facebook later concluded it wasn't worth anywhere close to the US$15 billion market value implied in that investment.

Because Facebook has only about 850 employees worldwide, getting complaints answered can take a long time. Istanbul, whose father is from the city of Istanbul in Turkey, said it took three weeks to get her account reinstated.

Without being able to log in for that time, she said she felt "completely cut off" from her contacts. Frustrated, she wrote e-mails, then mailed letters to 12 Facebook executives. To keep in touch with her friends and monitor her business pages, Istanbul said she sort of "hijacked" her husband's account.

"I think they just assume you can't have an interesting name," she said of Facebook. "I kept my maiden name because it's such an interesting name, I didn't want to give it up. And now I am having to defend my name."

The suspension of Robin Kills The Enemy's account inspired a friend to create the group "Facebook: don't discriminate against Native surnames!!!" on the site. The group has more than 3,200 members, including some with Native American last names who've had their account disabled.

Causing offence

"If you deal with this kind of thing all the time, and on top of that Facebook wants you to prove your identity, ... it's adding insult to injury," said Nancy Kelsey, a graduate student at the University of Nebraska in Lincoln, who started the Facebook group. She said Facebook should remedy the problem so that it "wouldn't be so offensive" each time a real name is deemed fake.

"Native American surnames mean something," she said. "They are points of pride, points of identity. It's not someone trying to make up a fake name."

Istanbul's sister, Lisa Istanbul Krikorian, also got locked out of her Facebook account, which she opened a year and a half ago. So she opened another one that omits her maiden name. Their mother and their cousin, who both joined the social network more recently, were not even allowed to sign up under their real names.

"They had to misspell their last names," Alicia Istanbul said, so that Facebook's system of weeding out fake accounts wouldn't recognize them. Her mom added an extra "n" to spell "Istannbul," and her cousin added an "e" to become "Istanbule."

The last name Strawberry also raises a red flag with Facebook, so to get around the namebots many Strawberrys have resorted to misspelling their names - to "Strawberri," "Sstrawberry" or "Strawberrii."

But that makes it difficult to reconnect with old classmates and long-lost friends, something Facebook prides itself in helping facilitate. "No one is going to find you if your last name is spelled wrong," Istanbul said.

Unlike many other social networks, Facebook wants a real name behind each person's account.

Facebook says its "real name culture" is one of the site's founding principles. It creates "accountability and, ultimately, creates a safer and more trusted environment for all of our users," Schnitt said. "We require people to be who they are."

Once the site disables an account it deems fake, its holder has to contact Facebook to prove it is real. In some cases, the company may require that the person fax a copy of a government-issued ID, which Facebook says it destroys as soon as the account is verified.

Yet an informal search on Facebook shows that efforts to weed out fake names may be a Sisyphean task. A recent search for "stupid," for example, turned up more than 27 people matches, most looking dubious at best. They join some 20 "I.P. Freely" accounts and 13 "Seymour Butts."

Although many of the fake accounts are created as sophomoric humor or as a vehicle for malicious activity, others are to protect users from having their postings create problems when they later look for jobs or apply to school. Facebook has extensive privacy settings, but they are complicated and many people don't know how to properly use them.