My avast! 5 IS experience so far is that whenever anything is deleted at the conclusion of an on-demand scan, avast! reports a "virus in the operating memory" and prompts for a restart and boot scan, Even the non-virus 'eicar.com' is apparently "unleashed" and becomes a threat during deletion.
Not only is this impossible, it makes it looks as though avast! is not able to unable to remove an identified but benign threat without allowing it to attack your PC.