Some Web site operators are complaining that Google is flagging their sites as containing malicious software when they believe their sites are harmless.

At issue is an "interstitial" page that appears after a user has clicked on a link within Google's search engine results. If Google believes a site contains malware, the page will appear, saying "Warning - visiting this Web site may harm your computer!"

Google does not block access to the site, but a user would have to manually type in the Web site address to continue. Organizations are complaining their sites do not contain malicious software, and the warning is embarrassing.

"We have no bad software or installs or anything that would indicate a need to ban people from viewing our site," wrote Matt Blatchley, who works for the Greenbush Southeast Kansas Education Service Center, in a posting on Friday to Google Groups.

Google's warning page contains a link to stopbadware.org, a project designed to study legal and technical issues concerning spyware, adware and other malicious software.

Stopbadware.org is lead by Harvard Law School's Berkman Center for Internet and Society and Oxford University's Internet Institute, in addition to vendor partners such as Google, Sun and Lenovo.

Stopbadware.org said on Thursday it had received information from Google on the issue. Google makes a determination of whether to flag a Web site based on its own independent scans of the Internet, according to a question-and-answer page.

Stopbadware.org, however, will review Google's decision if a user submits a query to appeals@stopbadware.org. Google will remove the page if the Web site is free of badware.

Organizations with Web sites prompting the Google warning chaffed at the appeals process. An automated e-mail from Stopbadware.org said it would reply within 10 business days.

"We understand that this may be an incredibly frustrating situation for you," Stopbadware.org said. "However, we have found that Web site owners are often not aware that their sites contain or link to badware."

This could occur, Stopbadware.org wrote, if a site contains advertising from third parties that has links to other Web sites with malware. Also, an organization's Web server may have been hacked, or the site itself could have been hacked using a security exploit.

The IDG News Service is a Network World affiliate.