It would be better in that case on demand scanner displays result of scanning in pop up notification instead of showing practically blank window only option to Run smart Scan. Also no such results displayed in Scan History if on -demand scanner as quoted by you actually runs. I have tried opening files from & saving edited files to USB drive. But in scan history, no record of on demand scanning seen. Also earlier at start of windows, system scan would run along with boot time scan and results displayed but in newer versions this doesn't happen. I am using Avast Premier not free Antivirus. Only thing in name of on demand scanning that happens when you open files from USB drives or attachments, a huge black window is displayed blocking you from using PC till you close the window.