The forum has since gone offline.

McAfee confirmed it had pushed the faulty update to users earlier today. "McAfee is aware that a number of customers have incurred a false positive error due to incorrect malware alerts on Wednesday, April 21," said company spokesman Joris Evers in an e-mail reply to questions. "The problem occurs with the 5958 virus definition file (DAT) that was released on April 21 at 2:00 P.M. GMT+1 (6:00 A.M. Pacific)."

According to users on McAfee's support forum, today's update flagged Windows' "svchost.exe" file, a generic host process for services that run from other DLLs (dynamic link libraries).

"HOW THE F*** do they put a DAT out that kills a *VITAL* system process?" asked on one thread. "This is goddamn ridiculous," added Gerard, who identified himself as a senior security administrator with Wawanesa Mutual Insurance Company of Winnipeg, Manitoba, in Canada. "Great work McAfee! GRRRRRRRRRRR."

As of 3:30 p.m. ET, McAfee's support forum was offline, with a message reading "The McAfee Community is experiencing unusually large traffic which may cause slow page loads. We apologize for any inconvenience this may cause."