Just for people's info.
I spent yesterday evening struggling with the non-working Start menu for build 1709 (as per above posts). When I came in tis morning, I started up and was immediately able to get the Start menu fully working. Yay. Wondered if there had been some invisible patch or something
However, to check, I did a restart and it was back to failing again.
What I finally realized was that I had started my machine and left it at the start screen while i made breakfast. I distinctly heard a notification come through (it turned out to be a new Java update), then when I logged in, I was able to get the Start menu perfectly. I tried a few restarts, not waiting, and the Start menu failed each time. So I tried to leave it sitting at the start screen as before until the notification happened. Again I was able to perfectly start the Start menu. Don't know if this is of any help.
I also noticed that when the Start menu failed and I did a restart/shutdown, I got a message that the Task Handling Window was hanging trying to close something, and I had to force the issue.
Anyway, now having a working system, I decided to rollback to 1703, which I did - no more problems! Roll on new update.