Within the Avast AV GUI, I scheduled a full scan at 5am every morning. The "Full system scan.txt" report file shows that it took place. However, when I fired up the laptop from standby at around 9:30pm, Avast started scanning, completing about 100 minutes after. This too was entered into "Full system scan.txt". I don't recall, but I might have gotten a dialog box saying that a scan had stopped, and perhaps I was asked to resume. I don't know why I'd be asked to resume (assuming that it happened), since the report file shows that the 5am scan stopped at 5:56am (almost 1 hour, but much less than the 9:30pm scan)). The report file shows that the total scanned files, folders and size stats are almost identical to the 9:30pm scan, so I doubt that the 5am scan was interrupted by the machine going into standby. As well, standby is set to occur after only with 15 minutes of idleness, and I'm assuming that scanning does not constitute idleness.
What would cause an unexpected scan such as the unscheduled 9:30pm scan?