No such problem here. I don’t use the browser extension from avast because I don’t think it can do anything good to me apart from messing around with the website by slowing it down or crashing the browser maybe. Many such problems are already reported here.
Make a clean installation, without the browser extension. You only require the fileshield and webshield and firewall if you are using AIS for optimal and more than satisfactory security. All other are junks! Disable webshield and check when you start the next time.