tangor - 9:40 pm on Jul 20, 2011 (gmt 0)

Google is issuing warnings to people whose computers are infected with a type of malware that manipulates search requests. A strain of rogue anti-virus software also includes a search hijacker component. The hijacker is designed to further enrich scammers by redirecting users of compromised machines through various dodgy pay-per-click affiliate sites instead of genuine search engines. Instead of going straight to Google, surfers on compromised machines are sent via proxies. The traffic generated from malware-infected machines has an unique signature that has allowed Google to return warnings to victims using these machines.

[theregister.co.uk...]
This, of course, since it does hit their bottom line...