MacBook locked up black screen with circle with slash

Logged on to my MacBook as usual. Put in password. Would not load then screen went black. Then white circle with a slash through it appeared. I tried logging in as “guest” but will not load Safari or any other page. I am connected to internet. When this happened, we were in a hotel and I put in hotel password, hit enter. My Kasperski window popped up and said “unsecured server”. To shut down and try again. Did that and that he is when I got the black screen trying to get back on after restart.