Still working to isolate the problem. But I am getting close.
Either my hard drive has decided to fail at the same time as a new update has occurred or there is something about logging out. Before, occasionally, I would logout and the screen would just lockup and I would have to go into Task Manager and stop the DnDclient process. No big deal.
This hard crash is a big deal. And so far, it has only occurred three times and each time has been when I logged out and exited the game.
It is possible that the new update has gone to some bad part of the hard drive as I don't think anything else was updated yesterday on my machine.
As I said, I am working to isolate the problem. This is in case others are having the same problems. I am nowgoing to read some of the other problems people are posting about.