No problem, glad I could help.
In cases like this I feel it is better to do a clean reinstall when the current version isn’t the latest one and more so after an infection.
If it were the current version, then I would have suggested an avast Repair as a first option.
The problem with many of these fake alerts, they require a degree of complicity, allowing them to download/run a scan, etc. If you see one of these alerts the best option is to use the task manager and end process for the browser.
I would also suggest using firefox and the NoScript add-on as this really does put a crimp in these drive by downloads, as all scripts on the page are blocked unless explicitly allowed.
Welcome to the forums.