I very much doubt that the log files will show anything significantly different from the log already posted earlier, but an extra check is always good.
I do agree with Tech that the issue of ZA still being in your system is worth following up. I understand that you are not starting ZA at system startup, but that does not mean that some components of ZA are being loaded into your system and may be affecting the avast update process.
I would recommend that it would be worth completely uninstalling ZA and seeing if that does allow avast to perform its update successfully.