DEP is a security measure implemented by Microsoft, to prevent malicious software, such as viruses, from running (or executing) code from your system's memory. You can disable DEP by:
1. Go to Start, right click on Computer, and then click on Properties. Now in the System window click on Advanced System Settings in the left sidebar
2. In the System Properties Windows, under Performance click Settings
3. In the Performance Options windows, navigate to Data Execution Prevention tab and select the second option “Turn on DEP for all programs and services except those I select:”