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Boot scans, also called shoe scans, or pre-boot virus scans, are advanced tools that antimalware software employs to remove malware that might not have been detected by standard scanning programs. This type of scan is able to run at regular intervals or can be manually invoked by the user whenever they suspect that their computer is infected. Many antivirus tools allow users to select the degree of sensitivity for the boot scan and also decide on the actions that should be taken if the threat is detected.

The reason why a boot scan is so efficient is that it allows the antimalware program to detect files that are being used by the operating system. These types of files cannot be deleted as they are always being used by the OS and will give an Access Denied error when attempts are made to erase them. The boot scan will detect these files and allow antivirus software to delete them before the OS can use them.

The length of a boot-scan can vary based upon a variety of aspects, including the speed and amount of system files being scanned. It also is contingent on whether the machine is being used during the scanning process. It is however common for this type of scan to take considerably longer than a typical antivirus scan due to the extensive nature of the process.