When performing a full system scan, the indicator within the program constantly rotates showing it is scanning. You should change this to a Progress Bar or Circle to show the extent of the scan, and to give the user an idea when the scan will complete.
As it stands now, I need to use my PC for other tasks, and am hesitating, waiting for the initial first time scan to complete.
Other competitors, btw, advertise a feature where the first scan is the longest but subsequent scans will be shorter. Don't know whether you have this feature.