Incase you dont know, Security Shield is a fake Anti-Virus Program that was put there by a trojan. I had alot of trouble removing this, but im going to tell you how I did it.
It looks like this:
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1. Finding the application...
Step 1: Go to 'Control Panel' and search 'hidden'
Step 2: Under Folder Option Click 'Show hidden files and folders'
Step 3: Look for "show hidden files, folders, and drivers", click and apply.
Step 3: Go to following location: > Computer > Local Disk (C > Users > "Your Username" > AppData > Local
Step 4: In this File, scroll down and you should see a shield, remember the application name....



2. Closing the application...
Step 1: Open Task Manager : Ctrl+Alt+Del or Ctrl+Shift+Esc (Windows 7) .
Step 2: Under 'processes' look for the file name found in 'Finding the application'
Step 3: Click on it and 'End Process'
Note: If you could not find it under 'processes' it may be named a series of number in there.



3. Deleting Security Shield...
Now that you have ended the process, you may do the following.
Step 1: Head back to the file: > Computer > Local Disk (C > Users > "Your Username" > AppData > Local
Step 2: Delete the icon with the shield.
Step 3: Your Done!


Note: It is recommended that you run a security scan after since a trojan put this here in the first place.