try to restart the computer. It remainds me a situation when an “old” avast! was uninstalled, new was installed however for some reason the “old” avast service wasn’t removed correctly. It may sometime happen (e.g. if you have open services.msc window, etc…)
Restart, check it. If it won’t help - use aswClear to wipe out everything of avast! and try once more time. It will definitely work.