Interesting, folks. All the responses are most appreciated.
I just double checked every thing and…
I noticed that the USB selective suspend was enabled! So I have disabled it. I really thought that I had gone through all possible solutions but this could certainly have been the problem!
My thanks to all of your for your responses. Hopefully this was the root of the problem and I will be crash free! Needless to say, this was very frustrating for me as it had happened several times. So, again, a very warm thanks to all for the help!