Microsoft Office 2010 has a number of security features. Data Execution Prevention (DEP) is a new security feature of Office 2010 that causes your program to stop when add-in code doesn’t meet certain criteria. When you restart the program, a message alerts you to the potentially dangerous add-in. DEP helps protect your computer and network from accidental bad code, or code with malicious intent.
When Data Execution Prevention is enabled in Office 2010, Office programs may stop responding (crash) when an add-in tries to run in a manner that does not comply with the computer’s security policy. When a Data Execution Prevention violation occurs, the Office program will stop responding to help protect your computer. When you restart the Office program that you were using, you receive the following message:
We recommend that you disable the add-in to prevent future crashes. In addition, obtaining a newer add-in, which is written to work correctly in a DEP-enabled environment, is advised
Office 2010 Security video: trusting add-in creators