Microsoft's latest patch updates released this week accidently flagged Google.com as malicious.

Microsoft's Technet support forums lit up on the subject, revealing that a user's malware inspection had been updated to 1.119.1972.0 which flagged Google.com as hosting the Blackhole expolit kit (JS/Blacole.BW).
A Microsoft Support officer said on the forum that the company had received several reports on the bungled update.
"Currently I'm working with our AV team to investigate the issue. Will keep you updated for any progress.”
Security blogger Brian Krebs said the alerts appeared to be the result of a false positive detection shipped to users of Microsoft's anti-virus and security products, most notably its Forefront technology and free Security Essentials anti-virus software.
He said that following a reboot, Internet Explorer claimed Google.com was serving up a severe threat and that Google's homepage was infected with a Blackhole Exploit Kit.
Krebs said clicking the default ‘remove' action prompted by Microsoft's anti-virus technology did "virtually nothing".