I've been getting Side by Side error 72 messages in the Event Log after installing the latest version of MSE. This was driving me nuts - even though it didn't appear to be causing any instability in the OS. After hours of messing around with the error I've finally been able to correct it by editing the .dll file.
The message in your event viewer may look something this;
Activation context generation failed for "c:\program files\microsoft security client\MSESysprep.dll"
Applies To: Microsoft Security Essentials | Getting Started and Upgrading
Log Name: Application
Date: 01.08.2011 03:51:24
Event ID: 72
Task Category: None
Activation context generation failed for "c:\program files\microsoft security client\MSESysprep.dll".Error in manifest or policy file "c:\program files\microsoft security client\MSESysprep.dll" on line 10. The element imaging appears as a child of element urn:schemas-microsoft-com:asm.v1^assembly which is not supported by this version of Windows.
To fix the error;
Open up the MSESysprep.dll file located (Windows 7) at %\program files\microsoft security client\MSESysprep.dll using a third party editor such as Notepad++ or ResourceHacker. You can delete the contents and replace with the text below, otherwise manually edit it to read exactly like this;
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- Copyright Â© Microsoft Corporation -->
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<description>Microsoft Security Client Sysprep module</description>
Save changes to the file and reboot. Your errors will be gone