NEW YORK -- Computers in companies, hospitals and schools around the world got stuck repeatedly rebooting themselves Wednesday after an antivirus program identified a normal Windows file as a virus.

McAfee Inc. confirmed that a software update it posted at 9 a.m. Eastern time caused its antivirus program for corporate customers to misidentify a harmless file. It has posted a replacement for download.

McAfee could not say how many computers were affected, but judging by online postings, the number was at least in the thousands and possibly in the hundreds of thousands.

McAfee said it did not appear that consumer versions of its software caused similar problems. It is investigating how the error happened "and will take measures" to prevent it from recurring, the company said in a statement.

The computer problem forced about one-third of the hospitals in Rhode Island to postpone elective surgeries and stop treating patients without traumas in emergency rooms, said Nancy Jean, a spokeswoman for the Lifespan system of hospitals. The system includes Rhode Island Hospital, the state's largest, and Newport Hospital. Jean said patients who required treatment for gunshot wounds, car accidents, blunt trauma and other potentially fatal injuries still were being admitted to the emergency rooms.

In Kentucky, state police were told to shut down the computers in their patrol cars as technicians tried to fix the problem. The National Science Foundation headquarters in Arlington, Va., also lost computer access.

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

Peter Juvinall, systems administrator at Illinois State University in Normal, said that when the first computer started rebooting 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.