Since April 18, the company has issued multiple advisories for its Threat Prevention 10.x, Host Intrusion Prevention 8.0, and Virus Scan Enterprise 8.8 software, warning that a patch to Microsoft's Client Server Runtime Subsystem (CSRSS) caused a deadlock with its software.
First, antivirus software runs at a privileged level on the system and in the critical path of many system operations.
Second, Microsoft is updating the core components of Windows more frequently than in the past.
Antivirus firms' continued reliance on undocumented function calls to give their software an advantage in scanning the operating system could cause future incidents of incompatibility, says Gabe Landau, principal software developer with Endgame.
"While antivirus companies can test for compatibility against past, current, and upcoming patch versions of Windows, it's always a risk when assumptions are made about undocumented Windows behavior because that behavior can change, breaking assumptions," Landau says.
"Sophos has received reports of computers failing to boot," the company stated in an advisory.
"Sophos is actively investigating this issue and will update this article when more information is available." Meanwhile, security firm Avast has issued a "micro-update" that fixes the issues its software has with the updates to Windows 7 and Windows 8.1, a spokesperson stated.So far they've probably been too aggressive with update cycles, and that may be why they've added the new feature to allow for scheduled or declined version upgrades." It's unclear how the increasing incidents of incompatibility will impact antivirus makers' products.Microsoft has its own antimalware software, and late last year announced it is running in a sandbox, making it less likely to be the target of a privilege escalation attack and further protecting the system.Check this Fix It to reset Windows Update components, and this Fix It to repair Windows Update components.Please check which Fix It applies to your version of Windows. To manually download the latest definition updates for Windows Defender: When the definition file runs, a file extraction dialog box appears.Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.