<A target="_blank" href="http://www.pcworld.com/article/192000/bad_bitdefender_update_clobbers_windows_pcs.html?tk=rss_news">A faulty anti-virus update from BitDefender caused 64-bit Windows machines</A> to stop working. The update falsely identified any "working" files as infected with a Trojan. BitDefender has issued a fix.