bob3160
3
Sorry Eddy,
It has nothing to do with Windows 8.1 I just updated 6 computers all running Windows 8.1 to avast! 2014
without any problems. 
@jmmug,
Glad you solved your problem and happy that the Third Party Support didn’t get you money. 
If you have a problem, please ask it here. There are many of us who would gladly help without charging for that service. 