Having problems with websites for awhile here also. Using updated Internet Explorer 11, & Avast Free version 2014.9.0.2011, some websites not working correctly, for example I am unable to successfully login to my ISP’s website among others. Tried logging in on another computer without Avast using IE11 and was successful. Tried disabling Avast Web Shield but was unsuccessful & then re-enabled Shield. Tried disabling the Avast IE Browser Addons & then was also successful. I hope this problem is corrected soon.
I had to disable webshield completely in order to be able to do my work online. As a result I did not feel adequately protected so uninstalled Avast for another AV. I will come back to Avast when they sort out all their recent quality issues.