When system updates I now receive a red box instead of the blue box I used to get . The red box advises : An Error has occured while updating.I click on the red box for more info and I get this message :
Last encountered error :Cannot connect to download10 avast.com (Unknown: 80)
I have uninstall avast and re installed program , I have inserted the License key , but still the same message keeps coming up, I’m sure its something very simple.
Thanks Maca
Hello Maca and welcome to the avast! user forums,
What kind of firewall are you using? Are you setting it to let all of avast! access the web?
Hi Justin ,
Thanks for the reply
Zone Alarm , I know I was advised that Zone Alarm may not be conpatible with Avast but it was working fine for about 2 months , then it started playing up
Maca
Check the Zone Alarm Program settings, look for avast.setup if you find an entry for it, delete it. Now doa manual update and ZA should ask again, allow avast.setup full access.
There have been cases in ZA were for some reason even though avast.setup is allowed access the underlying settings aren’t recognising this.
ZoneAlarm free is fully compatible with avast.
ZoneAlarm pro requires ajustments in WebShield settings, but it’s fully compatible too.
OK . I have gone into ZA programs and for some reason Avast was denied access to Internet. I have changed setting so that avast can access internet and then I manual updated avast and this has worked.
Thanks guys 
Glad we could help, welcome to the forums.