First thing I have done is to disable Windows Defender real time and the active center showed after that two warnings, no antivirus and no antispyware software instead just only no antivirus message. But Avast was running correctly.
Then I downloaded the Avast uninstaller, another antivirus and that other antivirus uninstaller.
In safe mode I used Avast uninstaller but I said no when the uninstaller asks if you are sure you want to remove all files in the folder (it shows such a warning that I clicked no trying to stop the process to start it again from scratch, but the process continued anyway uninstalling all the rest). So it uninstalled everything of Avast (browser extensions, the registry entries including the run on startup, …) but not the files. I restarted and the action center was showing still the same messages no antivirus no antispyware. And what was very curious still showed Avast reporting it was not active (don’t know how active center works to show that message but was showing Avast on the message). This message were in red, marked as errors.
Then I installed the other antivirus (which is a trial that I have not rights to use anymore) and restarted and it showed perfectly its state. The active center was reporting correctly that antivirus XXXXX was not active temporarily -because it needed to be registered-, both as antivirus and as antispyware. This was a warning, marked with a yellow color. It was not an error in red.
Then in safe mode I used that other antivus uninstaller and restarted once more. Again the active center was showing no antivirus no antispyware, reporting Avast was not active.
So again I restarted into safe mode and I run the avast uninstaller. I selected the avast folder as this time that folder was not filled in the uninstaller automatically, and continue with the uninstall. Now all Avast files were removed. I restarted and this time the active center was showing no antivirus, no antispyware. The antivirus section showing no product names at all and the antispyware software saying Windows Defender was not active.
Finally I reinstalled Avast and restarted. And the active center shows correctly that Avast is active as antivirus and antispyware. Hope it continues that way.
So, I don’t know exactly how the active center works but most of the times it is showing the correct state of things. And for all the years I have been using computers and those are a lot, the only problem I have seen till now in the active center related to security software that I remember, is for some months this annoying message that is saying Avast is not active when it all indicates is running correctly anyway. Besides it all indicates that when an antivirus is running is that antivirus the one that reports its state to the active center or at least is what I imply considering the message about that other antivirus I tested was explaning very clearly what were going on -something is impossible for the active center to show unless the antivirus itself reports it to the active center-.
Maybe you are right and it is a Windows bug. But for my experience on these tests it all indicates is a problem on the running antivirus not reporting correctly its state to the active center for some reason.
Besides considering what happened to me today I’m now not sure if the other time I tried to do a fresh installation -some days ago- I did it correctly or maybe I did same mistake when using the uninstaller in safe mode not removing the whole Avast Software folder from Program Files. So maybe I did not a clean install but an installation over the previous Avast files.
I will see in some days if it is indeed a bug on Windows (if the issue comes back I will be more inclined to accept that) or a problem in Avast mayor update (from Avast 8 to Avast 2014) that is solved with a fresh install.