Im having a similar problem. I had to system restore my computer from a checkpoint. Since that, Avast does not work for me. I can not uninstall it, I cant re download it, I even re-bought the product for a year and I already bought it a week again before that...
It keeps saying "Fix Now" and when I click it, It says, "Would you like to allow this to make changed to your computer?" and I say yes. Then it says it 2 more times. and nothing happens.
I have restarted my computer like 5-10 times now.
I can open the program, and under summary/ current status. It says "The avast antivirus program has been stopped, or is in an inconsistent state. Please re-start the program to resume protecting your system." and once again, I cant when I click to do that.