The update to the Windows family of operating systems, specifically for Windows 7 and Windows Server 2008 R2 or for Windows 8.1 and Windows Server 2012 R2, released on April 9, is causing problems with antivirus software. In recent days, Microsoft has been adding more antivirus scanners to its list of 'known issues.' As of now, the list includes antivirus software from Sophos, Avira, ArcaBit, Avast, and now McAfee.
It seems that computers with the latest Windows update and antivirus software from these vendors work fine until an attempt is made to log in, at which point the system becomes unresponsive. It's unclear whether the system hangs altogether or just operates very slowly. Some users report that they were eventually able to log into Windows under their user accounts, but the process took them ten or more hours.
Meanwhile, booting in safe mode works as usual, and it is currently recommended to use it to disable antivirus applications and boot the system normally afterwards. The company Sophos also , states that adding its own antivirus directory (i.e., the directory where the antivirus is installed, such as C:Program Files (x86)SophosSophos Anti-Virus) to the exceptions list on its own resolves the issue, which seems a bit odd.
Currently, Microsoft has halted the rollout of the update for users of Sophos, Avira, and ArcaBit, while McAfee is still investigating the situation. ArcaBit and Avast have released updates that should fix this error. Avast leaving the system on the login screen for about 15 minutes, and then rebooting the computer, during which time the antivirus should update automatically in the background.
Avast and have expressed their views on the root cause of the problem, stating that Microsoft made changes to ("Client/Server Runtime Subsystem") is a key component of Windows that coordinates and manages Win32 applications. Reportedly, this change literally puts antivirus software into a deadlock. The antivirus tries to access some resource, but is denied since it already has exclusive access to it.
Since the fixes came from antivirus manufacturers and not from Microsoft, this may suggest that the change made by Microsoft in CSRSS uncovered hidden bugs in the antivirus software. On the other hand, it's also possible that CSRSS is now doing what it logically shouldn't.
Source: 3dnews.ru
