Updating windows 8 has no effect against this particular issue as my system was completely up to date at the time this happened. I was forced to run windows 8 system restore to go back to the point just before Avast free was installed.

After the system restore was completed, I reinstalled Avast free antivirus. With this done, I changed the setting in the behavioral shield to uncheck the option “Monitor the system for unauthorized modifications” and restarted the system. Unchecking this option seems to have resolved the problem of the black screen at logon, but my installation of Google Chrome (installed along with Avast Free Antivirus) is broken, and won’t allow to run in windows 8 mode (Metro)

Again I’ve run system restore to undo the avast installation, and installed google chrome without avast free antivirus installed, and had no problems with chrome that way.

The solution appears to be choosing custom install and unchecking the behavioral shield to prevent it from being installed at all. Allowing it to install gives it the opportunity to block several things that windows does on it’s own before you can disable the option to prevent unauthorized modifications.