In a hasty effort to keep abreast of the continuing onslaught of viruses and malware McAfee released a set of virus definitions that flagged as malicious a core file of Windows XP Service Pack 3. McAfee disables this file, and after a reboot the system is rendered useless. Learn more in this PC Mag Blog. If you have a positive for w32/wecorl.a don't shut your computer down, read this article, or call your IT support! McAfee admits they did a poor job with quality control on this one, but don't make a hasty change to another AV without doing your due diligence. Many other vendors have had their shares of mis-steps over the years.