@ cwtlr
These advanced automated on-demand scan options are only available in the Pro version.
My own feeling on this is you should use the default interactive action. This way you know exactly what is going on with your system. After you have done this once, with the resident on-access scanners, there is less likelihood of infection getting on your HDD to be later detected on an on-demand scan.
You don't say what type of scan you did, Low, Normal or Thorough and if Archives were included ?
Archive (zip, etc.) files are by their nature are inert, you need to extract the files and then you have to run them to be a threat. Long before that happens avast's Standard Shield should have scanned them and before an executable is run that is scanned. Thorough is also by its design very thorough and perhaps a little overkill for routine use, were a Standard scan without archives should be adequate.
I have only ever done a through scan with archives once shortly after installation just to ensure a clean start state, but with XP for example avast will do a boot-time scan after installation if you select it, this I believe will be quicker and reasonably effective. Like everything in life things are a compromise.
@ al968
On-access settings aren't applicable for on-demand scans.
