On Monday, Avira released “Service Pack 0” for all of its Windows products. Once the update was installed, the “ProActiv” behavioral monitoring component in Avira Antivirus Premium 2012 and Avira Internet Security 2012 blocked the execution of essential programs and trusted system processes. For example, ProActiv blocked the Windows registry editor (regedit.exe) and the task scheduler (taskeng.exe).
As the behavior recognition is only included in the company’s commercial products for 32-bit versions of Windows, the problem does not affect Avira Free Antivirus or users who run a 64-bit version of Windows.
Those who are affected by the problem need to update Avira manually; once the update has been installed, the ProActiv module can be reactivated. For systems where Windows is having difficulty booting, users are advised to start their systems in safe mode and install the Avira update.