If the permissions are not set properly on the Applications folder, the Mac Antivirus cannot load several plugins. Therefore, please use the "Disk Utility" to analyze and fix this issue.
If you receive one of the following error messages, please proceed as described bellow.
1. Open "Disk Utility" and click Macintosh HD.
2. Click Verify Disk Permissions.
3. Click Repair Disk Permissions.
Your problem is solved if the function Verify Disk Permissions displays a sentence like:
"Permissions differ on “Applications”; should be drwxrwxr-x ; they are drwxrwxr-- .".