It's an unpleasant experience for me to see that this problem has occur again in build V 22.0.0.110 .
When back all they way to the first public beta release until the version right before V 22.0.0.110, NS beta has not problem in performing any on-demand scan with WIndows 8's fast start-up enable. But after I given a try to the latest beta release since 3 days ago, I can confirm that this problem has come back again. Scan like quick scan will not run when selected.
I really hope Symantec can rectify this issue asap before the final version is released.