I use Avast 2014 free & Win 8.1 x64.
When I install Avast to my computer, my computer can’t access to other computers & printers in LAN (wireless but wire LAN is ok).
And I disabled all shield of Avast is my computer can access to other is ok.
Please give me a solution.
Sorry for my bad English, thanks >.<
what firewall do you have?
do you have other security programs installed?
what antivirus did you use before installing avast?
did you uninstall it before installing avast?
did you use the vendors removal tool?
My computer only have Windows Firewall and I 've disabled it.
I only use Avast and don’t install any Anti Virus or Malware, Removal Tools, I install Windows and then Avast Free.
Try help me, plz.
try to remove browser protection, reboot and see if that changes anything
see picture at bottom of this guide
http://www.avast.com/en-eu/faq.php?article=AVKB96#artTitle
report back…
I only choose File Shield & Web Shield, and don’t install any tools of Avast as Browser protection, Software Updater, …
It could be that some setting in avast (deepscreen, hardened mode) is preventing a driver (wifi or printer) to be used.
It would help if you post a screenshot of some Avast alert when you try to print or try to connect to another computer.
And do turn your Windows firewall back on 
Because my computer is old, I disabled deepscreen & hardened mode, this components made my pc is slowly.
Avast don’t have any popup alert. When install Avast, all LAN network is disable,I can’t connect any pc or printer. When I disable Avast, all is ok.
We need diagnostic logs…
See instructions here https://forum.avast.com/index.php?topic=53253.0
Scroll down to Farbar Recovery Scan Tool and attach logs