When you say “entering this new “.avastlic” => same bad message” - how are you entering this ?

Two ways:

  1. copy and paste the activation code into avastUI or Insert License file, which normally gives an explorer style window and you locate where you saved the license file on your hard drive.

  2. you van save the license file to your hard disk and double click on the license file and avast would insert the license into avast.

I’m at a bit of loss as to why the license file would work with older versions yet not with the latest version. As you mention this doesn’t seem to have lots of others with this issue otherwise we would be seeing much more activity about it in the forums.

I don’t believe that you can’t get infected through a corrupt registry as such.

I think the next step would be to submit a support ticket - Try the following: https://support.avast.com/support/tickets/new. In the meantime I will try to attract some attention to this topic.