@ ::Seeker:: The OP stated that even after seven hours avast still showed the scan stuck at 0%.
That alone points to something other than scan settings. That gave me good reason
to suggest a repair and since that failed the next logical step would be a clean install.
@ OP The one thing I forgot to ask is, what other security software do you have now or ever had?
If uninstalled, how was it uninstalled? Also what are you using for a firewall? ???