Event 1042 - UIPI Cross Process Window Message
Applies To: Windows 7, Windows Vista
User Interface Privilege Isolation (UIPI) prevents application processes running with lower privileges from using Windows® messages to send information to a higher privilege process. For example, if you are running as a Limited User, Windows Internet Explorer® 8 and Internet Explorer 7 prevent Web sites from sending messages to the Microsoft Management Console (MMC) or to an Administrative Control Panel (CPL). This blocking process helps to protect against "shatter attacks". A shatter attack is when one process tries to elevate privileges by injecting code into another process by using Windows messages.
When Is This Event Logged?
This event is logged when an application process running with lower privileges attempts to use Windows messages to send information to a higher privilege process.
For more information and examples, see the Event 1042-UIPI Cross-Process Window Message topic from Internet Explorer Application Compatibility.
There is no fix for this compatibility issue. You must modify your extension so that it operates within the protected mode integrity checks. For guidance on writing extensions that are compatible with Internet Explorer protected mode in Windows Vista® and Windows 7, see the article Understanding and Working in Protected Mode Internet Explorer on MSDN.