A user a one of our client's site was experienc an issue where a Symantec Antivirus full scan was started when the user logged in every morning.  The scan was scheduled to run at 1:00 AM, but it seemed to be ignoring the schedule.  The problem was caused by the computer being in sleep mode during the evening when the scan was scheduled to run.  The scheduled scan would not bring the computer out of sleep mode to run the scan at the scheduled time.  As soon as the started to login the computer would come out of sleep mode and the scan would start.  The power saving options are a per use setting.  Without group policies in place, this setting must be completed for each user on each computer.