I know this post is old, but I’m having kind of the same problem.

I uninstalled avast. restarted… and avast loaded…
I try to uninstall it again (I’m just learning you needed the utility) and it said the installation or uninstallation was corrupt or whatever.
So I come here, learn about the utility, try it…

Avast has a self-defense mechanism, says I have to disable it.
So I go where it says, uncheck it. Try again.
Said the same thing.
I open avast again, go to maintenance, troubleshooting, and self-defense mode is still checked… -.-

So I uncheck it AGAIN…
and again…
and again…
and again…

its still recheckint itself…
now really… um… wtf…?