"According to messages on AVG’s support forums and its own support site, an update released late Saturday for the company’s security software fingered the "user32.dll" file as a Trojan horse. As per the program’s settings, the AVG software, including the newest version 8.0 and its predecessor 7.5, shut the .dll away in quarantine. The result: A crippled computer.
"If you have chosen ‘heal’ or ‘quarantine,’ your PC will no longer restart," said a panicked user named "pa3bar" in a message Sunday . "It shows a blue screen at start up and tells you it cannot find winsvr, error c0000135. System recovery has no effect." " – Content courtesy of Flawed AVG antivirus update cripples Windows XP PCs | InfoWorld | News | 2008-11-11 | By Gregg Keizer, Computerworld