Mountain Lion sometimes hangs when mouse enters Dock – pointer is movable, but the MacBook Air seems otherwise frozen I have a mid-2011 13" MacBook Air (MacBookAir4,2 with Intel HD Graphics 3000).

Since installing Mountain Lion I sometimes encounter a problem when I move the mouse cursor over the dock to click something.  

Sometimes I get pinwheeled, sometimes I don't. 

Whenever the problem occurs: 


there appears a 75% transparent label for a dock item
I can continue to move the mouse
the computer does not recover, I resort to a forced shutdown. 


There doesn't seem to be any common denominators yet, other than it always happens as I mouse over the dock.

Is there a log or anything I can look at to rectify the problem?
Not a solution to the problem, but I found that closing the lid and waiting until the computer sleeps (status led pulsing) and opening it works.
At least its better than a forced shutdown right?