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i heard from my friend that avast deletes the file if there is virus in my d or e drive
is that rite?
i do not want my important file get deleted.
avast 'doesn't delete' anything that you don't tell it to delete.
avast alerts to infection and depending on the avast version you have (avast 4.8.) then
you decide what action to take on every detection.
avast 5.0 has a list of Auto actions on detection, delete is
not a first response in the auto actions that is, Move to Chest is the first action. You can change the default auto actions to deal with it as you wish.
Spend a little time browsing the avast help file and have a look inside the program setting to get to an idea of what it does, rather than listen to speculation.