Kernel not connecting in Jupyter

[Alex Storrs]

I installed anaconda3 and opened a new Jupyter notebook and worked through much of the introductory material and saved the notebook. When I restart and load the notebook, there are no "out" lines and a message in the ribbon at the top says "Connecting to Kernel"

Is this a local or systemic problem? How can I address it?

Many thanks!

Alex Storrs