During what seems to be routine scans about once a week my Avast (version 6.0.1367) dicovers "infected" files and in the process of "healing" them it deletes a good file (pkzipw.exe) that I use regularly.
Can anyone tell me how to stop that?
What do you mean by healing them ?
So when is this file detected, e.g. what scan and what malware name does it give it ?
Avast doesn't delete anything autonomously, the default action on detection is move to chest unless the user selects the action to delete.