UPDATE: I am now running Avast 2014 v2014.9.0.2007 and I have just retested and confirmed that the "restore default power settings" now works as designed on my rig. I am also up to date with all Windows 8.1 updates applied. Hopefully it will work for everyone else as well. Any chance Avast could have snuck in a streaming update to fix this issue? Anyway, good luck to all.
plsrepli