An update on my experience of ashDisp.exe hanging when I shutdown.
It hasn't happened for a while. AFter the discussion here and the useful information I gleaned, I checked my VRDB setting, which was 'Generate VRDB only when screen-saver is running'. Hmmmm! I don't have a screen saver. I set VRDB to 'Generate VRDB when computer is idle' and then, a short time later, I saw the spinning 'I' which hadn't been apparent before. Since that time, no more ashDISP on shutdown. I haven't gone back and checked if I can get the hangs again if I return to the prvious VRDB setting but I will shortly when I am pretty sure the problem has gone away.