In Windows VistaCurrently, there are conflicts between a security feature integrated in Internet Explorer 7 and browser plug-ins. In this regard, the browser's security settings can lead to the plug-ins becoming inoperable. "Because browsers can host plug-in extensibility, security settings within the browser can make plug-ins fail. This is why in Internet Explorer 7 Data Execution Prevention (DEP) is off by default. When it is enabled many plug-in components fail to run, often crashing the browser," explained Michael Howard, Microsoft Security Engineer.
I must mention, as you can see in the adjacent image, that the Internet Explorer 7 I am referring to is the one in Windows Vista and not the versions for XP. In Windows XP IE7 does not present the feature.
Two of the most extensively used browser plug-ins are Adobe System's Adobe Acrobat/Reader browser helper object and the Adobe Flash Player. Following the latest updates introduced to the Adobe software products, both the Adobe Acrobat/Reader browser helper object 8 and Adobe Flash Player 9 now support the Internet Explorer 7 Data Execution Prevention capabilities.
Adobe Flash Player 9 delivered complete functionality with Internet Explorer 7 since November 17, serving as a model of implementation for IE7 Protect Mode and browser extensions interoperability.
In order to enable DEP in Internet Explorer 7 running on Windows Vista, navigate to Tools, Advanced and then scroll towards the bottom of the settings box. Due to compatibility issues, the "Enable memory protection to help mitigate online attacks" is disabled by default. If you have downloaded and installed the latest updates from Adobe Systems go ahead and check this box. The Adobe Acrobat/Reader browser helper object 8 and Adobe Flash Player 9 will work fine.
Moreover, you must make sure that additional browser plug-ins do not interfere with the settings. In the eventuality that IE7 crashes or that the plug-ins fail, simply disable the feature.