Where and what are you trying to copy ?
Basically you can only copy from the text based files mainly in the Report or Log sub folders:
C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\report XP location.
C:\ProgramData\AVAST Software\Avast\Report Vista, win7 or later. This is a hidden folder and you may need to change windows explorer folder settings to view it.