After updating Windows 7 Ultimate 64bit to 1473 via the Avast GUI under the Maintenance tab, the computer locked up after reboot. I had to restart in safe mode and run system restore to get back to 1466 and now the computer is working properly again. I did not have Webrep installed prior to update and have not installed it now. Firefox 16.01 and Internet Explorer 9 are working properly. I have my copy of Avast set to manual for the program update options. From now on I will wait for a week or so after new program updates are released before installing them, after reading the forums during that week of course.
Since I posted the information above, I updated a different machine running Windows 7 Ultimate 32 bit with 1473, but this time via the notification link on the status screen and it worked without issue. Both of the machines are running the same security applications, Malwarebytes, Spybot S&D and Windows Defender.