I was having this issue with the previous update, missing parts of pages, pixelated images, pages that wouldn't load. Along with this problem I was getting an occasional BSOD when connected to my router webpage, which was also displaying with corruption. At first I thought it was the router as the ISP had recently put out a firmware update, but after typing up a very angry message to them I thought to disable Avast, problem solved. Clean installs of Avast and using the avastclear tool did not help. Same problems on IE11 and Chrome.
Turns out it was the new Web Shield acting up. I had to add
[General]
UseStreamFilter=0
to the webshield.ini as mentioned by a moderator here
http://forum.avast.com/index.php?topic=144850.msg1051475#msg1051475 and all my problems were fixed, despite that fix being for another problem entirely.
I'm sorry to hear people are suffering from the same/similar problems. I'm refusing to update Avast again until I know this has been fixed, an AV shouldn't be causing issues with basic functionality and shouldn't be crashing properly configured systems.
Now I have to go and check why a realitve's Avast update has stopped all of their facebook games from working