Lets see the steps for avast boot scan fix automatically.

• Open the avast antivirus and got to the protection
• Then click the gear icon
• Select your boot time scan tab and install the latest version.
• Scroll down to search for the option to perform automatic action during this scan.
• Restart the window PC. when you start your system, a boot time scan progress screen will appear.
• This scan will take some time, and control the program and files.
• After that windows will boot automatically.