You can also go directly to the source of the information that is displayed in the avast log viewer, the text files, Warning.txt in the C:\Program Files\Alwil Software\Avast4\DATA\log folder.
Now if you have stuff in the Info section of the log viewer, you have changed the default setting in the Program Settings, Logging, which is set with the slider opposite the Notice level. This generates more log entries and also windows event log entries.