WHY do virus appears even after healing the files with AVG -antivirus??

when i switch on my laptop,the scanning begins with avg anti virus n everyday a huge number of files (which i think are the same files) are infected (backup copy n movable objects)....how do i remove these MS-DOS ,WINDOWS and TROJAN horse viruses completely.... do i need to format my laptop???plsss help!!!

WHY do virus appears even after healing the files with AVG -antivirus??norton

AVG is a poor antivirus program get a better one, in the mean time turn off system restore %26 do a free on line scan:

http://www.bitdefender.com/scan8/ie.html

When clean turn system restore back on.

WHY do virus appears even after healing the files with AVG -antivirus??spyware remover

See if your anti-virus can remove the trojan.
Purchase a good anti virus/spyware CD at the computer store. The free ones are weak.
Get some of these programs listed below.All these software work very well,they are the leaders in the current market.

Kaspersky anti-virus:

http://kaspersky-anti-virus.antiviruspro...

Kaspersky internet security:

http://kaspersky-internet-security.antiv...

Norton Anti-Virus 2008:

http://norton-anti-virus.antivirusprotec...

Norton 360 All in One Security

http://norton360.antivirusprotector.info

Norton Internet Security 2008 :

http://norton-internet-security.antiviru...

Good luck!