I was able to create and run EICAR AV test file while the on-access protection running ??? ???
I am not the only one how faced this problem, Read
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1121;start=0#lastPost
But the problem was fixed after uninstalling the program, deleting “…\Program files\Alwil” folder and reinstalling it again…
(Eicar file was cought )
So, do not upgrade from your version to the latest one. Just uninstall the old and install the new… ;D