Hi Everyone,
We are aware of the issue with windows 8.1 and currently investigating. We hope to have a fix as soon as possible. To the guys that have reinstalled, when you uninstalled, did you use Avastclear or just uninstall through the control panel? IF through the control panel, try the avastclear utility and let us know if you still have issues.
We know this is not an ideal fix, and hope to have more info soon.
Thanks!