No need now. I have none of these issues now. I just restarted my system and everything was back to normal. No issues in action center, I can open avast!
Close this topic and close the other I made?
Restarting is another workaround. The issue will happen again soon. In my case, It's been happening since I installed W8.1.
I think this is a bug waiting to happen. Sooner or later, it will screw up everything again.
I have Avast Premier + Malwarebytes. I'm going to ignore Action Center from now on!