tedster - 8:30 pm on Oct 16, 2011 (gmt 0)
Google has been known to have occasional technical issues of their own when it comes to domain roots - incomplete polling from the data stored at a particular back end server and the like. They apparently store at least some domain roots in a dedicated location. Then they need to import and integrate those domain root lists into the production environment's complete data set. That kind of thing used to happen relatively often in years past.
In terms of your own possible technical issues, have you used one of the online DNS check-ups to see if there's any possibility of someone messing with your DNS cache in a periodic way?