An update to antivirus software for corporate customers of McAfee Inc., caused much difficulty for customers running Windows XP with Service Pack 3 installed. The company has released a statement via it's blog saying:
In the past 24 hours, McAfee identified a new threat that impacts Windows PCs. Researchers worked diligently to address this threat that attacks critical Windows system executables and buries itself deep into a computer’s memory.
The research team created detection and removal to address this threat. The remediation passed our quality testing and was released with the 5958 virus definition file at 2.00 PM GMT+1 (6am Pacific Time) on Wednesday, April 21.
McAfee is aware that a number of customers have incurred a false positive error due to this release. Corporations who kept a feature called “Scan Processes on Enable” in McAfee VirusScan Enterprise disabled, as it is by default, were not affected...
Guess it's damage control time! I'm amazed that this sort of thing doesn't happen more frequently considering the frequency of updates issued and the nature of the files that are potentially affected.