Trend Micro apologised on Monday for distributing a faulty software update that caused IT workers around the world to spend the weekend fixing their systems.
The Japan-based antivirus company has promised to compensate customers whose computers running Windows XP SP2 were disabled by the update. The company said the update was only available for ninety minutes and caused "certain performance issues" with CPUs, but IT managers are furious.
"This damn update took down virtually all 1,500 of our Windows XP SP2 PCs and required many hours of work to resolve," said one angry reader in an email sent to ZDNet UK. "The machines were rendered inoperable once this signature hit, and required many of us to work through Friday night. Our entire IT staff had to come in on Saturday to attempt to fix this disaster."
"How in the world could Trend [Micro] release a signature file that disables all Windows XP SP2 machines? Why didn't [they] test this signature before it got released? I cannot believe that Trend Micro has no XP SP2 machines to test on before they release patches, and if they don't they better get some ASAP. If this happens again, I can assure you that we will be finding a new antivirus vendor for our organization," he added.
A second reader reported that every one of his company's 250 desktops had to be visited by a technician and repaired after being hit by the problem.
Trend Micro, which denied rumours that the update included a virus, said it didn't know what had caused the incident but that it had now issued a fix and was working with channel partners to solve the problem.
"We apologise to the people and we are willing to compensate them for the extra work they had to do their machines," said Raimund Genes, president of Trend Micro for Europe. "It's a pattern file that we made a mistake on. I would say this is an isolated incident, but we have to figure out why it wasn't caught by the quality assurance."
A Trend Micro spokeswoman later said that compensation claims would be assessed "on a case by case basis".
Genes said that most of the businesses affected were located in Japan, and that few complaints had been received from customers in the US and Europe.
Investors of the company have been informed, but Genes said the incident could affect share prices.
"I just talked to the [chief financial officer]. Of course it has an impact on stock today. We haven't decided what kind of compensation we will offer."
The update affected versions 7.5 and above of Trend Micro's Scan Engine. The company said it changed a decompression algorithm in the update file to combat a rise in the number of viruses that recruit PCs for bot nets.