A preview version of Internet Explorer 6, a future release of Microsoft's Web browser, has been made available prematurely over the Web by at least two specialist software sites. The beta version had been distributed by Microsoft to a small group of software testers, who typically are made to sign non-disclosure agreements that prevent them from sharing the software. Somehow a version wound up in the hands of two sites aimed at software enthusiasts, The-Ctrl-Alt-Del and FileClicks, which offered the program for download from their Web sites. By Monday afternoon, The-Ctrl-Alt-Del had pulled the plug on the download after learning through news reports that Microsoft was investigating the matter, said Eric LeVasseur, the site's editor-in-chief and senior Web developer. The beta was available on the site for about 18 hours before it was pulled, and was downloaded by thousands of people, LeVasseur said. Late Monday the FileClicks site was still advertising the availability of the file although users were redirected to the site's front page when they attempted to download it. A brief selection of messages on the site's message board also included a link to a Russian FTP server where the software had apparently also been available, but attempts to access that site failed. Microsoft didn't immediately return a call seeking comment. LeVasseur wouldn't say where he obtained the software beta. Disclosing that information could result in "major consequences," he said. "I don't feel bad, because I'm not stealing anything," he said. "It's not as if this is the next operating system ... This is software that will be free" with a future version of Microsoft Windows. "I'm running it right now and it's pretty good," he said, adding that the program is "not finished." Judging from the screenshots posted on the Web, the future release has a similar look and feel to the current version of Internet Explorer. The upgrade includes an "Explorer bar" down the left-hand side of the screen, which contains shortcuts to favourite Web sites and to some of Microsoft's own Web properties, LeVasseur said. "That's one option I'm not used to," he said. "I looked everywhere to take it off, but I couldn't find a way. You can customize it to include your favourites; it's like a properties bar."