Defender virus - isn't actually a virus and it doesn't harm your computer it just prevents you from using your computer. Defender is a small application written for marketing purposes for users to purchase anti-virus software from that advertising company.
Once you're infected with this virus every window and application you had opened will be closed, access to any installed applications will be denied because defender.exe will inform you that application you're trying to run is infected with a virus.
Don't be alarmed there is a way out. Just follow these steps.
1. Restart your computer through Start->Turn off Computer>Restart or hard reboot using the button on your computer case. In case you don't have a restart button on your case (as some new cases no longer have it) you can press and hold the Power button until your computer shuts down. Once computer has shut down just press Power again to boot it up.
2. Enter Safe Mode. Depending on your computer manufacturer how you enter Safe Mode may differ. To enter Safe Mode, press and keep pressing F8 button on your keyboard (some computers have this as F10 or F12) once you performed Step 1, which is restart your computer.
3. Select Safe Mode from the Menu and press Enter. Wait for computer to load fully. Once you get to user login screen you can select your username which you usually use. Don't use Administrator account unless your own account doesn't work. Safe Mode will disable all normal programs or services to load; only the necessary ones for the Windows to operate will be working.
4. Open Control Panel, open Folder Options icon and select the View tab. In the Hidden files and folders section select "Show hidden files and folders" and click OK. You can close control panel now.
5. Open My Computer, then C: drive and follow to this path: C:\Documents and Settings\[your-account]\Application Data\. In this folder find and delete the file defender.exe. Close all open windows.
6. Press Start->Run. In the prompt dialog type "msconfig" (without quotes) and click OK. A new window will open, when that happen select the Startup tab (second last one).
7. Now, find defender in the Startup Item column and uncheck it. Then, press OK and when prompted to restart press Restart. Let your computer load normally. The defender virus should not load or pop-up any more.
Hopefully this article will help you free your computer from defender virus and allow you to proceed with your daily tasks.