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. Two of the most well-known and commonly used browser plug-ins, the Adobe Acrobat/Reader browser helper object and the Adobe Flash Player, now run when DEP is enabled. You can enable DEP by navigating to the following dialog and checking the highlighted option shown below (note, you must elevated to admin first, otherwise the option is grayed out).