The short answer to the question is YES!
Numerous factors are at play inside your computer. Your security software programs are one of those factors which can become affected by other software. For example; If your computer has Norton 360 AND McAfee installed AT THE SAME TIME then you will notice one of two things happening. First off, your computer will be SLOW immediately after the installation of the 2nd program. Secondly, you will notice spyware and viruses are evident inside your computer.
WHY?
Each program treats the other as if it COULD be a threat but it never actually gets the 
courage to prompt its user. Even if one or both programs are expired and need to be renewed, they are still functioning. Running these software packages during optimal conditions will lower your effective protection from an average of 70%-85% down to 10%, if either package is effective at all!
Here is what you are looking for:
You are looking for one good anti-virus program and one good anti-malware/spyware program. That is all you need. Windows Vista, Windows 7, Windows 8 (and beyond) all have a sufficient firewall in place. You do not need any other firewall as long as a modern router is in your home or office network, as these routers more than likely have a firewall built in.
We recommend utilizing our Managed Anti-Virus program which is $49.99 per year. We also recommend utilizing the FREE malware bytes program at www.malwarebytes.org. Since October 2013 we have seen a GREAT decrease in major virus infections when utilizing these two programs.
One thing we tell each of our clients who come to us infected is that regardless of what antivirus program you are running; you will always be your best protection against virus, spyware or malicious software infections. Even the best antivirus software is only 70%-85% effective.
