Where was this avastsetup.exe file as that isn’t an avast file I’m familiar with, avast.setup, a legitimate avast file that runs the update process, so if that is what you meant we need the message that was given ?

So if there was some issue with Microsoft (don’t know why it would become involved) and the avast.setup that could mean the update may fail.

I don’t know what you were actually doing in this full update, but essentially if just means downloading the virus database.

Avast! Manual Virus Definitions Update Download - avast! Virus Definitions Update - Manual Download ensure that you select the correct virus definitions (for avast 5, vpsupd.exe, approx 31MB). - Save the file to your hard disk, locate where you saved it and double click it and that should carry out the virus definitions update.