Workplace computers across the world got stuck rebooting themselves Wednesday after an antivirus program identified a normal Windows file as a virus.

Antivirus vendor McAfee Inc. confirmed that a software update caused its antivirus program for corporate customers to misidentify a harmless file. It has posted a replacement update for download.

Intel Corp. appeared to be one of the victims, according to employee posts on Twitter. Intel did not immediately return calls for comment.

Online users indicated that thousands of computers running Windows XP with Service Pack 3 were affected.

Peter Juvinall, systems administrator at Illinois State University in Normal, said the first computer started rebooting before 9 a.m. It quickly became evident that it was a major problem, affecting dozens of computers at the College of Business alone.

"I originally thought it was a virus," he said. When the tech support people concluded McAfee's update was to blame, they stopped further downloads of the faulty software update and started shuttling from computer to computer to get them working again.

McAfee shares fell 20 cents, or 0.5 percent, to $40.39 in afternoon trading.