Just went through the process; uninstalled, rebooted, rebooted into safe mode and ran avastclear.exe, rebooted, installed from offline installer.
When installation was finished a window popped up to say "You are now protected", I moved my mouse to the continue button, clicked, and again nothing happened. Couldn't close it, icon menu won't respond to clicks, all the same problems. Rebooted, same problem, rebooted again, same problem.