The caller was initially vague about his problem. Kent Campbell remembers uncomfortable silences and said the man on the other end of the line nervously cleared his throat again and again.

After some coaxing, the caller finally revealed that he was a doctor and that a blogger had posted scathing comments about him as well as his line of health and beauty products. The post appeared at the top of the list in a Google search using the doctor's name, and he said it had already caused him to lose $5 million from a potential investor.

Campbell, a kind of Sam Spade for the Cyber Age, had heard it all before. A self-described crusader against internet invective, he makes a living by restoring reputations sullied by insults posted anonymously on the internet.

"People who contact me are usually very embarrassed and sometimes very angry," he says.

Often for good reason. Three decades ago, former British Prime Minister James Callaghan said that a lie can travel halfway around the world before the truth has got its boots on; the internet has greatly widened that advantage.

Whether unjust, spiteful, or just plain false, a disparaging post on the first page of a Google search can ruin a reputation regardless of redeeming information found on pages two, three and four. As a result, combating defamation on the Web has become a booming business.

Within the last two years, several lawyers have begun to specialize in defending victims of cyberslurs and smear campaigns. And dozens of so-called internet reputation management companies like Campbell's in Ventura, California, have formed to prevent or mitigate the damage of negative Web postings.

"We're engaged in guerilla war against this type of stuff," Campbell says. "Sometimes I feel like I should be wearing camo."

To help the doctor, Campbell and his team of six employees and 25 contractors had to figure out whether this was a war or just a skirmish. Lucky for the doctor, it was the latter. The author of the negative posts was a random guy expressing his opinion rather than someone making a concerted effort to defame the doctor. This was not a cutthroat competitor or vengeful ex-lover, as is often the case.

Next, Campbell says they looked for any positive content that already existed online about the doctor. He had his own Web site with patient testimonials. And he had done a spot on a local TV news program.