ThreatFire AntiVirus Free Edition 3
Here is a different type of anti-virus protection compared to the traditional big names we have today. Rather than relying on daily updates, this software thrives on monitoring behavioral changes of your computer, something that leads to potential threats as far as you computer safety is concerned.
Through its behavioral analysis feature, it can help advise you on certain processes that your computer normally has and abnormally gets which can readily alarm you of the need to address the problem. A good aid for other anti-virus programs which cannot seem to determine erratic system behaviors.
You can download this here.
(Source) Download.com