First thing this morning I was able to use Firefox to read pages on the BBC website.
I started a full virus scan and Avast said an update was available so I installed it and then did a full virus scan.
After the scan had finished I tried to open Firefox again, the cursor turned into a blue rotating swirl for a few seconds, then changed back to an arrow and Firefox didn't start. The same thing happened when I tried to open Chrome and Thunderbird. When I tried to open IE the window opened, displayed (Not Responding) in the title bar for several second and then closed. When I rebooted into safe mode I could open the programs. When I uninstalled Avast in normal mode it fixed the problem. When I reinstalled it and updated it then the problem came back.
My PC is running Windows 7 Home Premium, SP1.
Firefox is 39.0
