Hi jghayes,
The log file is in the program data folder, which is sometimes hidden. If you go to C: drive and don't see program data then you need to unhide it. You can do that by following these steps (from Microsoft directly):
Open File Explorer.
Go to the C drive.
Click on view.
Check on the box Hidden items.
If you are still unable to see the program date folder then click on Options next to hidden items.
Go to view tab.
Under hidden files and folder, select show hidden files, folders and drives.
Click on Apply and OK button.
Now, again go to C diver the program date folder shall be available.
Once the program data folder is open, you can open the Avast Software folder, then Avast, then Log. The log for SecureLine is located here.
Please open a support ticket here:
https://support.avast.com/support/tickets/new and include the log file there.
Many thanks,
Davidek