Gary, the only way is disabling avast! Man, you are receiving a virus file and do not want avast! get rid of it? The Home version requires user interaction (unless sending the file to Chest by silent mode). Try the Pro version, where you have fully configurated options for the ‘automatic’ actions of avast!
Anyway, you can avoid the displaying virus ‘advice’ (yellow/red layer that pops up when a virus is found) configurating the avast ini file.
More information about it you can see here. See section [AAVM]. I’m trying to do my best to help you 