Avast! Internet Security 2015 disables internet connectivity

Hello–

After an automatic update of Avast! Internet Security, I discovered that I could no longer access the internet. I experimented with various combinations of shutting off Windows’ and Avast!'s firewalls and reached the point where connectivity
was restored for approximately ten minutes at a time. After that, I lost connectivity and had to reboot the system. Poking
around, I noted that something was wiping out the ipv.4 addresses.

Having wasted a day in researching the problem, I uninstalled Avast! and replaced it with the Comodo free antivirus package and the internet access problem went away.

Five months ago, I invested in a three-year, three-PC Avast! package-- I’m interested in a.) whether anyone else has experienced the problem, b.) when will it be safe to reinstall Avast!, or c.) whether I should write off Avast! and go with another brand of antivirus software. Comments are welcome!

System: Windows 7 Professional, Version 6.1 (Build 7601: S.P. 1); Firefox version 33.1.

I’ll let the experts here comment on your Avast questions but I’d like to hear your opinion on Comodo A/V.
There are a lot of reviews out there that say it is best thing ever but I hesitate those are all subsidized, biased articles.
I would find it interesting to see what a long time Avast user thinks of Comodo.