Microsoft Security Essentials

Insufficient software updates are a likely cause of Microsoft Security Essentials crashes. Be sure to install the latest updates for developer products.

Restarting your computer can resolve numerous common problems, so it should be the initial step before changing any software-related settings.

Changing Default Programs in Windows

1. Right-click on your file and choose the "Open With" option. Then click "Choose another app" to continue the process;
2. From the list of applications in the pop-up window, find and select Microsoft Security Essentials as your desired application;
3. Check the "Always use this app" checkbox, and then click "OK" to set your chosen app as the default for opening files.

Change Default Program on Mac

1. Initiate a right click or use Control + left click on the desired file to open a menu where you can select various actions;
2. Select "Open in application" and click "Other";
3. At the bottom of the window, you will find the "Enable" menu. Default, will be set to "Recommended Programs";
4. Within this menu, select "All Programs" and then locate Microsoft Security Essentials. Check the box next to "Always open in app" to set it as the default program.