might well be correct.
While he was posting, I took a slightly different approach, that is, to "Google" the URL that appeared in your browser as posted in your second picture here.
I'm going to assume that you didn't type (or have saved as a favorite) "newwayscanner.info
Your browser has been re-directed to this page, probably, which is, as you probably already know, for a malicious scam.
"Googling" the URL led to a few hits...quite few. It appears the malware is quite new..perhaps even from as early as August this year, and is thus not widespread, which is (if that is correct) why the scanners aren't detecting it.
The Google hits I looked at suggested that some users with other AV's failed to have it detected, also, so you are not alone.
(I realize that may not actually make you feel less annoyed.)
You might want to post a HijackThis log here. I'm not trained in the use, but there are folk who help here that are. It might be a way to find out what process is involved, stop it, and in the process send a sample to Avast. (Further info/instructions would be forthcoming.)
An alternative (less palatable, IMO), would be to wait until the scanners get samples and update their detections, so it can be removed by what you have installed already.
If you need instructions on posting a HjT log, please advise.
What firewall do you use?