For example my dad's PC caught the ZeroAccess pest and not one antivirus software could fix it at the time.
So it's clear that no one software can deal with them all.
So if it's some known infection then you research if there is a cure but sometimes the damage is too deep and it's best to start over.
-> The worst of the lot is RansomWare ( http://en.wikipedia.org/wiki/Ransomware ) where it can lock up the users files. Good thing everyone knows they only lose what they don't backup.
Bob
What kind of software do I need to cure or delete viruses?

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