I certainly haven't seen anything in the forums about this.
avast doesn't undertake autonomous actions like rename or delete user input is required for the Home version and in the Pro version you can set action on detection, but in the case of avast 4 home, the user would first have received an alert of an infected file. The pro user may not depending on how they set things up to react on detection. The key I guess is that these files would frist have to have been detected as infected in some way for any deletion or rename action to be taken.
This can be checked to see if a WGA file was detected as infected by checking the avast log viewer (right click the avast 'a' icon) and check the Warning section.
You can turn of the auto updates, however, the program updates are normally set to Ask so you would be notified if one is available asking if you want to install it now. I don't know about it being shown in the shutdown menu though, do you happen to have a screen shot ?
