Anti-virus software is not panacea for all that ails your computer. Anti-virus software will help you with many of the threats that attack your system, but there are some types of threats that all anti-virus software doesn't protect against.
Behavior blocking: Behavior blocking is a term used to describe technologies that block malicious applications from accessing parts of your operating system. Since all anti-virus application detect, clean, and prevent infections by using definitions that are signatures of threats, these must be updated before they can protect you against a new threat. An example of behavior blocking technologies would be to prevent a virus that sends emails to everyone in your address book from being able to access your address book. Another example of behavior blocking would be to keep a virus from terminating key processes that protect your system.
In memory threats: Most viruses infect a file, and the viral code runs when the application is running. Anti-virus scanners work by scanning files on the file system looking for virus. Some infections like W32. Slammer infect an application when it is running and are never written to disk. Since antivirus solutions scan for infections in files instead of memory that the application uses, they don't detect these types of infections. If an application is known to have an in-memory security exploit, the application should be disabled or terminated and patched immediately.
Hacking: Everyone has heard about hackers. Unfortunately, anti-virus software doesn't protect you against this type of attack. To protect yourself against these types of attacks, you need firewalls, intrusion detections systems, and constant vigilance. In the future, it is likely that these measures will be more tightly coupled with anti-virus software. One application that currently has an integrated suite of anti-virus, firewall, and intrusion detection system is Norton Internet Security.
Spy-ware: Spy-ware is a type of application that records information about how you use your computer. This is a problem that has been gaining more awareness in the past few years. Currently, most anti-virus solution don't scan for these types of threats. In order to detect or remove spy-ware, you need a spy-ware cleaner.
To get more information about all these problems and how to remove them, check out our website: Spyware Removal