It is not good to install avast in safe mode.
Which was your previous antivirus before avast and how did you uninstall it?
I suggest an installation from scratch:

  1. Download the latest version of avast! Uninstall Utility and save it.
  2. Download the latest avast! version and save it.
  3. (Optional) If you want, save your avast! settings for later restoration (Settings > Maintenance > Back up).
  4. Uninstall avast from Control Panel (if possible) and reboot.
  5. Run the avast! Uninstall Utility saved on 1 in and follow the instructions. Reboot in Normal mode after that.
  6. Install avast! using the setup saved on 2. Boot.
  7. Register your free copy or add the license key for Pro. Or even upgrade your key from old versions.
  8. Check and post the results.

Please, be patient, boot when it’s said to boot…