Because the people that write the coding for viruses continually update it to try and get past you AVP (Anti Virus Program).
Install virus software
I install aVast Anti-virus & I install FireFox & adobe Flash & reader then I check for windows updates.
You should have software to automatically check for updates. You can control when the updates are installed and added to your system.
Yes ,If you do not have the latest patches and the most updates anti virus software
you have to format your PC,automatic updates are turned off due to the virus which affect you computer
Computer Virus Signature are updates that has been downloaded mainly by an Antivirus program. These Virus Signature are patterns and behaviors of a virus. If your Antivirus detected a file and it's pattern and behavior the same as the virus signature, it will automatically list it as virus.
AVG Anti-Virus 9 is an excellent choice for virus protection. Updates are made regulary, and the software has received 5 out of 5 stars on cnet.com AVG provides great virus protection for your computer,it is rated very high. The best part is the basic suite is completley free including updates.
Set your anti virus program to do automatic updates. They need to be done as soon as they are available.
It is not a good idea to stop updates from Mcafee as there are new viruses created everyday and any new virus not protected by the old updates could infect your computer.
It will not run if the services are disabled by some virus or firewall
free at first then for updates it will cost 10.00 or more and it will cause virus
A CD will have been shipped with virus signatures at the time of its production. Your virus may be a later made virus and thus the disk, and the program on it, won't know of this particular virus until a update is applied.