I would like to run the Avast Registry Cleaner that removed all pointers to Avast then restart and re-install Avast 4.x or Pro.
To do an installation from the scratch you need:
1. Download the latest version of avast! Uninstall Utility
and save it.
2. Download the latest avast!
version and save it.
3. Uninstall avast from Control Panel (if possible). If, for any reason, you can't run it, try booting in Safe Mode
and doing it from there. Anyway, boot after that.
4. Run the avast! Uninstall Utility saved on 1. If, for any reason, you can't run it, try booting in Safe Mode
and doing it from there. Anyway, boot after you've run it.
5. Install avast! using the setup saved on 2. It will be good to accept the boot time scanning. Boot.
6. Check and post the results.