According to local media, Symantec's Norton software has mistakenly removed essential user files in the Windows XP operating system, believing those files to be viruses.

The problems came from the latest virus definition update issued last week, which caused millions of computers to collapse after they were re-started.

Norton's update deleted two system documents, lsasrv.dll and netapi32.dll, under Chinese Windows XP systems so users couldn't enter the system after they re-started their computer. Some users quoted in local media say that the harm Norton has done this time is more serious than that of Huigezi and Worm.WhBoy viruses. And lawyers say that Symantec may need to compensate the users for this big mistake, although it has made an apology to users and already amended the relevant files.

Symantec is a global leader in infrastructure software, enabling businesses and consumers to have confidence in a connected world. The software failure is deemed to be the most serious accident in recent years, and might be used as fodder by domestic Chinese anti-virus companies to show that overseas software vendors are aiming to hurt Chinese computer users.