Microsoft raced to fix an anti-virus program that targeted Google's Chrome browsing software as a malicious threat and kicked it off computers. Microsoft said the case of mistaken coding identity lasted about three hours and affected about 3,000 users. "An incorrect detection for PWS:Win32/Zbot was identified and as a result, Google Chrome was inadvertently blocked and in some cases removed from customers' PCs" (personal computers), Microsoft said at a malware protection Facebook page. An update to free Microsoft Security Essentials anti-virus software had mistakenly targeted Chrome as a troublesome computer virus tailored to steal online banking information. Microsoft apologized for the error.