You're welcome.
The Smart Scan has several elements to it, a combination of all of the scans, plus Network Security scan (I don't have a network established, GrimeFighter if you have it installed, so it is very likely to take some time.
It is possible one of these elements is hanging up and I think that may The GrimeFighter part - I did a custom install of avast and in the Tools section basically I uncheck everything other than the avast Shields and the Software Updater.
My last Smart Scan, I'm just running it now and all it is looking for is Viruses & Malware and Software Updater and it took 28 seconds and only scanned 252.7MB.
Generally I don't bother with on-demand scans, only in instances like this to confirm it is running.
- With a resident on-access antivirus like avast, the need for frequent on-demand scans is much depreciated. For the most part the on-demand scan is going to be scanning files that would be otherwise be dormant or inert. If they were active files then the on-access file system shield would be scanning them before being created, modified, opened or executed.
I used to have avast set to do a scheduled weekly Quick scan, set at a time and day that I know the computer will be on and not busy. But I have now abandoned that also.