If you're having problems, executing a restart is usually better than a shutdown. Shutting down doesn't purge cobwebs as well as restarting (it's often not much more useful than logging out and back in again). Shutting Windows down keeps some data around so it can boot faster (sometimes faster than hibernation).
In this day and age of computers never really powering off, it is perhaps bad form to refer to "power" unless a power chop has taken place. There's shutting down and waking up, and there's restarting. The whole time, there are things active in the computer.
Chopping power is perhaps more like a restart than a shutdown, as Windows recognizes that a proper shutdown wasn't executed, thus it shouldn't quickboot.