It's a worry that plagues every computer user: "What if my computer is
actually infected but my security software is not detecting the problem?"
It's a reasonable fear as some malware programs will disable your security
software while others can hide themselves in really sneaky ways to avoid
detection. Now I wish I could tell you that we have a 100% bulletproof way
you can check your computer for nasties but alas this is not possible. No
security software is perfect. However if you follow the procedure outlined is
this article you will be able to confidently determine if you have a malware
infection or not. Not 100% certain but close enough to give you peace of
mind.
http://www.techsupportalert.com/content/how-know-if-your-computer-infected.htm