Boot-time scan
It is possible to schedule a scan to be carried out automatically when the system restarts i.e. when it “boots”, before the operating system is active. This is useful if you suspect that a virus may have been installed on your computer, as it will enable the virus to be detected before it is activated and before it can do any damage to your computer.
In the “Settings”, as well as scanning the boot-sector, you can also specify other areas to be scanned automatically when the system restarts.
You can adjust the heuristic sensitivity by clicking on the orange bars to change the sensitivity to Low, Normal or High, or you can turn it off completely. The heuristic analysis comprises a large number of tests based on typical virus content or behavior and the sensitivity level will determine how many tests would have to be failed for a file to be considered as infected. The higher the sensitivity, the higher the “pass mark”, therefore the higher the chance that a file will fail the heuristic test and will be reported as a potential virus.
By default, the program automatically scans for potentially unwanted programs and also scans inside archive files, but either of these features can be turned off by unchecking the relevant checkbox.
You can also specify what action should be taken if a threat is detected. avast! can automatically attempt to repair the file, move it to the virus chest, or delete it. Alternatively, you can specify that you should be asked what action to take for each detected threat, or you can specify that no action should be taken.
Finally, click on “Schedule Now” and the scan will start automatically as soon as the system is restarted.