Well technically it's MS Windows Security Center that's blind to avast, and it worked just fine with avast until the MS Windows Vista SP1 update...so how on earth do I trace that smoking gun back to anyone besides Microsoft???
There is no McAfee on my system. That was a "grasping at straws" solution to begin with. Here is the sequence of events so newcomers don't have to read the whole thread:
1. Security Center and avast love each other very much.
2. They have a falling out after SP1.
3. Security Center now pretends that avast does not exist.
4. Avast doesn't seem to care, the little blue "a" ball spins merrily on the taskbar, as before.
One day when I'm not lazy I may try reinstalling avast. But I have already tried the "remove previous AV" route, and there is nothing there to remove.