McAfees anti-virus software is erroneously detecting legitimate Windows system files as malicious. SANS Internet Storm Center has received dozens of reports from McAfee users who complained. The error can result in moderate to significant performance issues on systems running Windows XP Service Pack 3. McAfee has removed the update from its download servers for corporate users, preventing any further impact on those customers. One symptom seems to be that McAfee reports that user systems are infected with W32.Wecorl.a.”]
Source: https://krebsonsecurity.com/2010/04/mcafee-false-detection-locks-up-windows-xp/