User Profile Cannot Be Logon

This is the third time I have ran into the problem, “the user profile service – service failed the logon. User profile cannot be logon”.   The second time with my computer and once for my mothers.  When I first ran into to this problem found a site that shows you how to fix it ( > here if you are looking) thought it looked way to complicated.  Going into the Registry  can look scary.  When this problem happened again to day it was a very quick and easy fix.  Still not sure why this happens but its a pain.  I can see if some one who doesn’t know much about computers this could scary them.