I think there is problem in the way Avast! chose which version of file to check. From what I see in Software Updater, Avast! was unable to define which version is stable, which is beta, so it show the version which is newer, doesn’t care if this is stable and officially released or not. In your case, your Chrome installer may be reported as old version and blocked. If you don’t mind, try a beta version (above 35) and see if it pass.