could you please share the log files so we can look at them to be able to identify the root cause of the issue?
Log files are located in this folder: [b]c:\ProgramData\AVAST Software\Tuneup\log[/b], please provide us with ALL files from that folder.
And you can either upload them to a favourite file server of yours or you can use our public FTP server for the purpose: ftp.avast.com/ftp/incoming/ (login: anonymous).