run the Best you got then run the Malwarebytes' Anti-Malware
http://www.malwarebytes.org/ and it will find bugs and problems the other one did Not catch.
we tryed for days over in PalTalk in our Tech room with these titles Most are just "BLOAT"
McAfee
AVG
BitDefender
avast
Norton
Kaspersky
eSafe
Avira AntiVir
eTrust Antivirus
Dr. Web
NOD32
F-Secure Anti-Virus
ViRobot Expert
Microsoft Security Essentials
eScan
Panda Titanium Antivirus
Sophos Anti-Virus