Uninstall avast via add/remove and follow the instructions. Download it’s removal tool from here https://www.avast.com/en-nz/uninstall-utility. Run it and the tool will tell that this tool will automatically run your computer in safe mode. Click ok on both and follow the instructions.
Next step is this:What previous antivirus did you have prior to installing Avast? Did you use it’s removal tool? If not, download it’s removal tool, turn your computer in safe mode, and run the tool.
Removal tool can be found here https://singularlabs.com/uninstallers/security-software/
After that has been done. Install a fresh new copy of avast. Once installed it will do a quick start up scan. Once done, restart your computer manually and register your copy of avast.
