Do you know that your anti-virus solution is working ? You could try to test your anti-virus program against the EICAR (European Expert Group for IT-Security) test file to see if it reacts the way it should. All you need to do is create the testfile and scan it with your virus scanner. If the scanner detects something it is working as intended, if it does not you should consider changing immediately to a more reliable one.
Creating the file is pretty simple. Just create a new text file and paste the following line of code into it: X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*
Save the file and rename it to test.com. When executed it displays the message EICAR-STANDARD-ANTIVIRUS-TEST-FILE. No harm will be done to your system if you accidentally execute the file. To test your virus scanner right-click the file and select to test it with your software.
You could also pack it and test it or send it to your email account to test the interaction between virus scanner and email client. After the test finishes you do know if your virus scanner is working as intended and able to detect viruses on your system. This does not necessarily mean that it will detect every virus that exists but it means that it is working.