Reuters reports that an update to Symantec's anti-virus software caused an undisclosed number of Windows PCs to crash, rendering them useless. The news arrives by way of customer complaints expressing their rage in a support forum on Symantec's website. The company has since acknowledged the problem and issued a fix.

A deeper investigation into the report reveals that a signature update to Symantec's Endpoint Protection software, a security package mainly used in the corporate environment, caused Windows XP computers to crash. More specifically, affected customers saw blue screens after applying Proactive Threat Protection definition version July 11, 2012 rev 11.

"This problem appears to occur only on Windows XP machines running SEP 12.1," Symantec reports. "Symantec has reproduced the problem and is now trying to identify the root cause. We have posted updated signatures which resolve the issue to the public LiveUpdate production servers."

To work around the blue screen issue, customers are urged to follow a list of steps on the impacted machine, located here.

According to the customers on Symantec's forums, it took the company "hours" to identify and fix the issue. They feel that Symantec should be responsible for fixing their blue-screened computers. "Phoning Symantec support this morning was the start of the hell we went through," one customer said. "The support is a joke, the quality control is a joke, and the software is not much better."

A Symantec spokeswoman told Reuters that the issue only affected "a subset" of customers, and would not confirm how many computers crashed due to the tainted update. However Ron van den Broek, a technology manager with Dutch company PSO Beheer BV, said the bug caused around 150 company computers to fail.

"It did have quite an impact on our business," he said. "My first impression is Symantec is downplaying the effects of this issue."

Another company, a Maryland-based insurance firm, told Reuters that it had to shut down the anti-virus software installed on all of its 150 computers to prevent the update, leaving the company without protection.

What's the story here? Now might be a good time to ditch the decrepit operating system if the funds are available.