Our entire IT staff had to come in on Saturday to attempt to fix this disaster.' 'The machines were rendered inoperable once this signature hit and required many of us to work through Friday night. 'This.update took down virtually all 1,500 of our Windows XP SP2 PCs and required many hours of work to resolve,' said one angry person in an e-mail sent to ZDNet UK. The company said the update was only available for 90 minutes, but IT workers are angry. The Japan-based antivirus company has promised to compensate customers whose computers running Windows XP Service Pack 2 were disabled by the update.

Trend Micro apologized Monday for distributing a faulty software update that caused IT workers around the world to spend the weekend fixing their systems.