Notebook problem with starting kernel

I was working with jupyter notebooks no problem, then suddenly I get an error message saying “Error Starting Kernal – Unhandled Error”. I now cannot start any of my notebooks. There are python message saying somethings are frozen.
Please advise how I can get around this. I have tried uninstalling Anaconda and re-installing but the problem persists, so I think it must be a windows problem. I am running Windows 10.