I’ve been running v 8 with no problems on Windows 8. On my boot up today, Avast updated automatically to v 9.0.2008 which I didn’t appreciate. Now there is no icon in task manager but when I hover the cursor over the “invisible” icon, I get the pop up saying the version and that “everything is good”. I can also right click and get the menu. Clicking the “Open Avast User interface” won’t launch the GUI. Nor will clicking on the desktop icon. Somehow the icon and GUI is suppressed. No other registry or anti-virus products installed.
You must have had “Automatic Update” set for the program?
Reboot a couple of times often brings everything back, if not run a repair
Control Panel
Programs and Features
Avast
Repair.
Once the repair is done, reboot the computer.