You can try looking at the raw text file report.
C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\report\WebShield.txt, XP location
Or
C:\ProgramData\AVAST Software\Avast\report\WebShield.txt, Vista or later. You may not have permission to access the ProgramData folder or it may be hidden, so you may need to adjust your permissions and folder settings to view hidden files and folders.