AVG update cripples some Windows XP systems

A false positive tags a Windows system file as malware, leaving some versions of Windows XP unable to reboot.

Robert Vamosi Former Editor
As CNET's former resident security expert, Robert Vamosi has been interviewed on the BBC, CNN, MSNBC, and other outlets to share his knowledge about the latest online threats and to offer advice on personal and corporate security.
Robert Vamosi
2 min read

On Tuesday an update for AVG 8 suggested that a Windows system file is a Trojan horse, and users who delete the file form the system could leave their Windows XP systems endlessly rebooting or unable to reboot at all. The problem only affects users of AVG 8 products running the Dutch, French, Italian, Portuguese, and Spanish language versions of Windows XP. AVG immediately sent out a corrected update to its customers, including those using the free editions of AVG.

A representative for AVG said, "AVG is actively working to remedy the problem some users are experiencing related to the most recent update to commercial and free versions of AVG 7.5 and AVG 8.0 in some languages. A number of users who installed the update mistakenly received a warning that the Windows system file user32.dll product version 5.1.2600.3099 was infected with a Trojan virus and were prompted to delete a file essential to the operation of Windows XP."

In response, the Czech antivirus company has posted details and a fix tool on its site.

For users unable to use their Windows XP machines, AVG says they "should contact their AVG reseller or ask a friend to download the information and fix tool for them."

AVG has suffered some embarrassing glitches of late. Last month, an AVG update declared some ZoneAlarm firewall files to be part of a Trojan horse. In July AVG had to reconfigure its Linkscanner tool after various Web sites complained about the increased traffic as a result of the tool's proactive scanning for malware.