On Win 7 Home Premium SP1 French, Firefox 26, FlashPlayer plugin 11.9.900.170, I have big issues (video sites, ADSL rate test, ...) after having updated Avast (Free, French) from 2013.8.0.1504 to 2014.9.0.2011.
All become Ok, if I desactivate the WebShield.
So, I have made the following actions :
1) Adding 2 new files (aswstm.sys 9.0.2011.265, and aswstm.sys.sum), made automatically by Avast, according Lucas post, dated 20 Dec 2013
No results
2) Activating "Scan the traffic from known browser only" in WebShield.
No results; So I turned back desactivating this line.
3) Implementing the Lucas patch (post, dated 31 Dec 2013) : replacing the 2 files (aswStreamFilter.dll, and aswStreamFilter.dll.sum) by the new files provided by Lucas.
I have let the 2 new files aswstm.sys, aswstm.sys.sum
A little improvment; Before : no videos seen, after : videos seen during 20-30 s, then freeze.
4) Implementing the change of WebShield.ini (adding UseStreamFilter=0), in the 2 identical files WebShield.ini located in C:\ProgramData\Alwil Software\Avast5 and C:\Users\All Users\Alwil Software\Avast5 (I did not change the WebShield.ini file, smaller and dated 8 May 2011, located in C:\Program Files\Alwil Software\Avast5\DATA).
I have kept the modifications made in 1) and 3)
All is Ok, in "old fashion" Avast mode according Lucas, but the most important is to have a WebShield activated.
I hope an update of Avast will rapidly solve the problem.
Thanks to everybody in this forum.