Solution for “antimalware service executable has encountered a problem” error with Microsoft Security Essentials on Windows XP

Update – Thursday April 17, 20:05 EDT : Apparently many folks running Microsoft Security Essentials report that applying the latest MSE Updates (by forcing an update from the Update Tab) to v1.171.106.0 of the virus signatures released yesterday at 22:00 UTC resolves the problem for Windows XP and Windows Server 2003

To manually install the virus signature updates (if it doesn’t work by doing Update from the Update tab) then you can download and install the 32 bit updates or 64 bit updates.

*** If anyone disabled the behaviour monitoring as suggested, once the updated signature is installed, reactivate it and see if things work better after a reboot. *** Remember this is only for Microsoft Security Essentials and only on WinXP or Win2003…

—-> I do NOT suggest entirely disabling real-time monitoring…. <—-



Original post from yesterday…



So a few people early this morning still running Windows XP reported that their machines seemed to have slowed to a crawl, barely responsive and almost as if infected with some sort of virus.

At the same time, they noticed an error message stating antimalware service executable has encountered a problem

At first I though it was just a fluke, but doing some research this evening, it seems that it was caused by an update to Microsoft Security Essentials (and other software packages) that include an antimalware protection component. Unfortunately it is buggy on certain older versions of Windows – including Windows XP.

One of the solutions (other than the obvious of upgrading to Windows 7 or Windows 8) while keeping Microsoft Security Essentials installed is to disable the ‘behaviour monitoring’ feature in MSE. This is based on an official Microsoft suggestion posted in their Microsoft System Center Support forum… it’s not the same product, but it does share the same affected antimalware component.

Important: do not uninstall MS Security Essentials if you’re on Windows XP unless you have another security or antivirus software package, as Microsoft no longer offers it for download from their site!

Behaviour monitoring is essentially what it sounds like – it is a heuristic analysis system that checks software ‘behaviour’ for patterns matching that of known or possible malicious actions and then takes action to limit the risk or quarantine the bad application. So it’s not an absolutely critical security component, but rather adds to the base security of scanning for antivirus signatures, etc.

Here is how to disable behaviour monitoring in Microsoft Security Essentials (see screenshot below):

1) Open MSE (double click on the status bar area on the bottom right next to the clock)

2) Go to the Settings tab

3) Uncheck the ‘Enable behaviour monitoring’ feature

4) Click on ‘Save changes’

Disable Microsoft Security Essentials Behaviour Monitoring

Again, this may not work for you, but if it does bring your system back to a more normal behaviour let us know in the comments below (please mention your operating system.)

Oh, and consider upgrading away from Windows XP sooner rather than later 😉

My readers got here searching for: