Google and Yahoo redirect my site to malware, but direct url works fine. Any computer

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http://serverfault.com – I can go directly to the site doublewing.org or www. without issue, but if I click on the link in google or yahoo it redirects to spam sites. Swagbucks works though! This is not on a single computer this happens on systems isolated from each other(Try it, avast blocks it) . The site is runing joomla 1.5.25 . I deleted .htacces, put fresh index.php and index2.php files. and still get the same results. Any ideas? (HowTos)